CN218100499U - Trigonometric function teaching and learning demonstration instrument - Google Patents
Trigonometric function teaching and learning demonstration instrument Download PDFInfo
- Publication number
- CN218100499U CN218100499U CN202222281874.1U CN202222281874U CN218100499U CN 218100499 U CN218100499 U CN 218100499U CN 202222281874 U CN202222281874 U CN 202222281874U CN 218100499 U CN218100499 U CN 218100499U
- Authority
- CN
- China
- Prior art keywords
- swing arm
- coordinate system
- linear
- trigonometric function
- rectangular coordinate
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Images
Landscapes
- Instructional Devices (AREA)
Abstract
The utility model provides a trigonometric function teaching and learning demonstration appearance, include: the device comprises a bottom plate, a linear rectangular coordinate system, a central shaft, a first swing arm and a second swing arm are arranged on the bottom plate, the central shaft is arranged at the origin of the linear rectangular coordinate system, one end of the first swing arm is connected with the central shaft, the other end of the first swing arm is hinged with the second swing arm, and the first swing arm is connected between the bottom plate and the second swing arm; the circumference of the bottom plate is provided with a circular ring-shaped angle scale mark which represents the angle scale mark of the triangle teaching and learning demonstration instrument; scale marks are arranged on the horizontal axis of the linear rectangular coordinate system and the longitudinal axis of the linear rectangular coordinate system; the second swing arm is evenly distributed with linear scale marks. Through the scale on the second swing arm and the scale on the rectangular coordinate system cross axis of linear bar and the rectangular coordinate system axis of ordinates of linear bar, can read out the sine value and the cosine value of integer angle by the right angle, solve teaching and study trigonometric function in-process except special angle, the problem that sine value cosine value need look up the table.
Description
Technical Field
The utility model relates to a teaching aid field, concretely relates to trigonometric function teaching study demonstration appearance.
Background
Currently, the current practice is. The trigonometric function is an important part of the mathematics in the first class as the content of the mathematics in the middle class. The trigonometric function relates to a plurality of theorems, definitions and formulas, and as some students cannot well understand the theorems, the definitions and the formulas, difficulty is easily met during memory and application, the effect of lessons of teachers and the learning effect of students are not ideal, so that the learning enthusiasm of the students is influenced, and difficulties are brought to students, teachers and even parents.
The inventor designs a trigonometric function teaching demonstration instrument in Chinese patent CN201521016486, which has a demonstration function of measuring trigonometric functions of special angles (such as angles of 0 degrees, 30 degrees, 60 degrees and the like), but has the defect that results cannot be directly obtained through the trigonometric function teaching demonstration instrument for non-special angles (other integer angles except for the special angles), and students still need to obtain trigonometric function values of the non-special angles in a table look-up mode during learning.
SUMMERY OF THE UTILITY MODEL
The utility model provides a trigonometric function teaching and learning demonstration instrument. For solving the problem that can not demonstrate the non-special angle trigonometric function most among the prior art, the utility model provides a trigonometric function teaching demonstration appearance can direct demonstration calculate the value of the trigonometric function of arbitrary integer angle.
The utility model discloses a scheme does:
a trigonometric function teaching learning demonstration instrument comprises: the base plate is provided with a linear rectangular coordinate system, a central shaft, a first swing arm and a second swing arm, the central shaft is arranged at the origin of the linear rectangular coordinate system and is hinged to the base plate, one end of the first swing arm is connected with the central shaft, the other end of the first swing arm is hinged to the second swing arm, and the first swing arm is connected between the base plate and the second swing arm;
the bottom plate is provided with a circular ring-shaped angle scale mark which represents the angle scale mark of the trigonometric function teaching and learning demonstration instrument;
the linear rectangular coordinate system comprises a linear rectangular coordinate system transverse shaft and a linear rectangular coordinate system longitudinal shaft, and scale marks are arranged on the linear rectangular coordinate system transverse shaft and the linear rectangular coordinate system longitudinal shaft;
and linear scale marks are uniformly distributed on the second swing arm from the hinge point to the other end of the second swing arm.
Furthermore, the scale mark on the second swing arm is radiated to the other end of the second swing arm by taking a hinged point of the second swing arm and the first swing arm as a scale mark zero point.
Furthermore, the second swing arm is rectangular and straight, one end of the second swing arm is a hinged end, and the other end of the second swing arm is a free end.
Furthermore, linear scale marks are uniformly distributed on the transverse axis of the linear rectangular coordinate system.
Furthermore, linear scale marks are uniformly distributed on the longitudinal axis of the linear rectangular coordinate system.
Furthermore, the scale marks on the bottom plate, the scale marks on the second swing arm and the scale marks of the linear rectangular coordinate system are bulges or grooves.
Furthermore, still include first swing arm recess on the first swing arm, first swing arm recess connection hinge point and the initial point of linear bar rectangular coordinate system.
Further, the bottom plate is circular.
Further, the first swing arm is rectangular and straight.
Further, the shape of the first swing arm groove is a long strip.
The utility model has the advantages that: scales are arranged on the bottom plate, the linear rectangular coordinate system and the second swing arm, so that the sine value and the cosine value of a special degree can be intuitively demonstrated, the sine value and the cosine value of a non-special angle can also be intuitively demonstrated, and table lookup is not needed.
Drawings
Fig. 1 is a schematic diagram of an embodiment of the trigonometric function teaching and learning demonstration instrument according to the present invention, when an included angle between a first swing arm and a cross axis of a linear rectangular coordinate system is an acute angle;
fig. 2 is a schematic diagram of an embodiment of the trigonometric function teaching and learning demonstration instrument according to the present invention, wherein the included angle between the first swing arm and the transverse axis of the linear rectangular coordinate system is greater than 90 ° and smaller than 180 °;
fig. 3 is a schematic diagram of an embodiment of the trigonometric function teaching and learning demonstration instrument according to the present invention, wherein the included angle between the first swing arm and the transverse axis of the linear rectangular coordinate system is greater than 180 ° and less than 270 °;
FIG. 4 is a schematic diagram of an embodiment of the trigonometric function teaching and learning demonstration instrument according to the present invention, wherein the angle between the first swing arm and the transverse axis of the rectangular coordinate system is negative;
fig. 5 is the utility model discloses the structural schematic of first swing arm recess in the first swing arm of trigonometric function teaching study demonstration appearance.
The reference numbers indicate:
1. a base plate; 2. a longitudinal axis of the linear rectangular coordinate system; 3. a horizontal axis of the linear rectangular coordinate system; 4. a central shaft; 5. a first swing arm; 6. a second swing arm; 7. first swing arm recess.
Detailed Description
In order to be right the utility model discloses a technical feature, purpose and effect have clearer understanding, now combine the figure, right the utility model relates to a trigonometric function teaching study demonstration appearance does further explain.
As shown in fig. 1, for the utility model discloses an embodiment of trigonometric function teaching and learning demonstration appearance, this trigonometric function teaching and learning demonstration appearance includes: the swing mechanism comprises a bottom plate 1, wherein a linear rectangular coordinate system, a central shaft 4, a first swing arm 5 and a second swing arm 6 are arranged on the bottom plate 1, the central shaft 4 is arranged at the origin of the linear rectangular coordinate system and is hinged on the bottom plate 1, one end of the first swing arm 5 is connected with the central shaft 4, the other end of the first swing arm 5 is hinged with the second swing arm 6, and the first swing arm 5 is connected between the bottom plate 1 and the second swing arm 6; the material of the central shaft 4 can be metal, plastic and the like;
the bottom plate 1 is provided with a circular ring-shaped angle scale line which represents the angle scale line of the trigonometric function teaching and learning demonstration instrument;
the linear rectangular coordinate system comprises a linear rectangular coordinate system transverse axis 3 and a linear rectangular coordinate system longitudinal axis 2, and linear ruler scale marks are uniformly distributed on the linear rectangular coordinate system transverse axis 3 and the linear rectangular coordinate system longitudinal axis 2;
and linear scale marks are uniformly distributed on the second swing arm 6 from a hinge point to the other end of the second swing arm 6.
As shown in fig. 3 and 4, when the angle α is greater than 180 ° and smaller than 360 °, the graduation line on the second swing arm 6 represents a negative value, for example, when the angle α is 218 °, the intersection of the second swing arm 6 and the horizontal axis 3 of the rectangular linear coordinate system can read out the sine value and the cosine value of the current angle, where the sine value is the inverse number of the value of the graduation on the second swing arm 6 at the intersection, that is, when the graduation value on the second swing arm 6 at the second intersection is 0.62, the inverse number is-0.62, and when the angle is 218 degrees, the sine value is-0.62.
The circular angle scale marks on the bottom plate 1 take the central shaft 4 as an original point, and the lines radially extending to the right side of the cross shaft 3 of the linear rectangular coordinate system are zero scale marks of the circular angle scale marks. The precision of the circular angle scale mark is 1 degree, the zero scale mark is used as a starting point, the circular angle scale mark rotates anticlockwise for one circle, namely the angle rotates from 0 degree to 360 degrees, the zero scale mark is used as a starting point, the circular angle scale mark rotates clockwise for one circle, and the angle rotates from 0 degree to-360 degrees. Since the progress of the angle scale line is 1 °, any integer angle can be measured by the first swing arm 5.
Furthermore, the scale mark on the second swing arm 6 is radiated to the other end of the second swing arm 6 by taking the hinged point of the second swing arm 6 and the first swing arm 5 as the zero point of the scale mark. The graduation marks on the second swing arm 6 represent the sine value in the trigonometric function, with the hinge point as a zero graduation mark, thus ensuring a sine value of 1 at an angle of 0 °.
Furthermore, the second swing arm 6 is rectangular and straight, one end of the second swing arm 6 is a hinged end, the hinged end is provided with a hinged point, a point of intersection with the first swing arm 5 is called the hinged point, and the other end of the second swing arm 6 is a free end. Be provided with the scale mark in second swing arm 6, design into the ruler form with second swing arm 6 for accurate reading, the one end of second swing arm 6 is the hinged end, and is articulated with first swing arm 5, and the other end of second swing arm 6 is the free end, and like this, second swing arm 6 can be along with first swing arm 5 motion and move, can 360 rotations. The thickness of the second swing arm 6 can be 1mm-2mm, the width can be 1cm-2cm, and the length can be 6cm-8cm. The second swing arm 6 can be made of transparent plastic, wood, metal, etc.
Furthermore, linear scale marks are uniformly distributed on the horizontal axis 3 of the linear rectangular coordinate system to represent cosine values of the trigonometric function. And scales are uniformly distributed leftwards and rightwards by taking the original point of the linear rectangular coordinate system as a scale zero point, when the scales are distributed rightwards, the numerical value is from 0 to 1, the precision is 0.01, when the scales are distributed leftwards, the numerical value is from 0 to-1, and the precision is 0.01. Therefore, cosine values of any integer angle can be directly read on the horizontal axis 3 of the linear rectangular coordinate system.
Further, linear scale marks are uniformly distributed on the longitudinal axis 2 of the linear rectangular coordinate system, and represent the sine value of the trigonometric function. And scales are respectively and uniformly distributed upwards and downwards by taking the original point as a scale zero point, when the scales are distributed upwards, the numerical value is from 0 to 1, and when the scales are uniformly distributed downwards, the numerical value is from 0 to-1.0. The precision of scale is 0.01, makes linear bar rectangular coordinate system axis of ordinates 2 and linear bar rectangular coordinate system cross axle 3 design keep the uniformity like this, and the scale appears wearing and tearing simultaneously on second swing arm 6, when unable seeing clearly, also can read sinusoidal value through the scale on the axis of ordinates.
Furthermore, the scale marks on the bottom plate 1, the scale marks on the second swing arm 6 and the scale marks on the linear rectangular coordinate system are bulges or grooves. The design of the scale marks of the bulges or the grooves can ensure that the scale marks are clearer and are not easy to erase, thereby prolonging the service life of the scale marks.
Further, as shown in fig. 5, the first swing arm 5 further includes a first swing arm groove 7, and the first swing arm groove 7 connects the hinge point and the origin of the rectangular coordinate system. The scale on the directional bottom plate 1 circumference of first swing arm recess 7 shows that first swing arm 5 is rotatory back, and the angle value of 3 contained angles of rectangular coordinate system cross axles of line shape, the present angle value of the trigonometric function that will calculate promptly, the line of directional angle is difficult by wearing and tearing in the design protection of first swing arm recess 7, can not hinder second swing arm 6 rotation simultaneously again.
Further, the bottom plate 1 is circular. The circular shape can be used for directly marking the circular angle scales, the circular shape does not need to be redrawn, the scale is convenient to manufacture, the bottom plate 1 is made of wood, transparent plastic, metal and the like, the scales are convenient to draw, the thickness of the bottom plate 1 can be 3-5 mm, the radius of the bottom plate 1 can be 5-7 cm, and the scale is convenient to carry and use for students to study and use and can be used for learning while playing anytime and anywhere.
Furthermore, the first swing arm 5 is rectangular and straight, the shape of the first swing arm is consistent with that of the second swing arm 6, the first swing arm is convenient to manufacture, and the first swing arm 5 is made of transparent plastics, metal, wood and the like, so that the prepared angle value can be read conveniently. The thickness of the first swing arm 5 can be 1mm-2mm, the width can be 1cm-2cm, and the length can be 6cm-8cm.
Further, as shown in fig. 5, the first swing arm groove 7 is in a long strip shape, so that the first swing arm groove 7 is visual and clear, and a straight line pointing to an angle is conveniently arranged in the groove.
The following describes the use method of the novel experimental trigonometric function teaching and learning demonstration instrument by using several specific examples.
1. Measuring any angle: if the bottom plate 1 is made of transparent materials, such as transparent plastics, the central shaft 4, the first swing arm 5, the horizontal shaft 3 of the linear rectangular coordinate system of the rectangular coordinate system and the scales on the bottom plate 1 can be used for directly measuring angles and being used as a protractor.
2. Demonstration and calculation of trigonometric functions:
as shown in fig. 1, 2, 3, and 4, the first swing arm 5, the second swing arm 6, and the horizontal axis 3 of the linear rectangular coordinate system form a right triangle, the first swing arm 5 is a hypotenuse of the right triangle, the length r of the first swing arm 5 is set to 1 unit, and the sine value of the angle α pointed by the first swing arm 5 is a scale value on the second swing arm 6 at the intersection point of the second swing arm 6 and the horizontal axis 3 of the linear rectangular coordinate system; the cosine value of the pointing angle alpha of the first swing arm 5 is a scale value on the cross shaft 3 of the linear rectangular coordinate system at the intersection point of the second swing arm 6 and the cross shaft 3 of the linear rectangular coordinate system. As shown in fig. 1 and 2, when the angle α is 59 °, the sine value is 0.86 and the cosine value is 0.52; when the angle α is 150 °, the sine value is 0.5 and the cosine value is 0.8, since the tangent value is equal to the sine value divided by the cosine value and the cosine value is equal to the cosine value divided by the sine value, it can be obtained:
3. demonstrating the variation of trigonometric functions:
1) Generalization of the concept of the angle: the horizontal axis 3 of the rectangular linear coordinate system is used as the initial side of the angle alpha, the first swing arm 5 is used as the final side of the angle alpha, and the first swing arm 5 rotates around the origin of the rectangular linear coordinate system, namely the vertex of the angle alpha to form angles with different angle values.
2) Angle of the same end edge: when the first swing arm 5 is rotated by a multiple of 360 °, the first swing arm 5 always stops at the same position, and the same angle β = K × 360 ° + α at the end can be demonstrated, where K is a natural number.
3) Demonstrating the change of sine function value and cosine function value: as shown in fig. 1 to 4, when the first swing arm 5 is rotated to have different angles with the positive direction included angle α of the horizontal axis 3 of the linear rectangular coordinate system, the change of sine values and cosine values of different angles can be demonstrated.
4) An induction formula for demonstrating trigonometric functions:
by adopting two trigonometric function teaching and learning demonstration instruments, sin (alpha) = -sin alpha, cos (alpha) = cos alpha, tan (alpha) = -tan alpha and cot (alpha) = -cot alpha can be demonstrated. The same corner of the terminal edge as described in connection with 2) above, stops at the same position, as shown in fig. 4
sin(-1479°)＝sin{(-4)*360°-39°}＝sin(-39°)＝-sin39°＝-0.63。
Therefore, when the angle is a negative number, the scale value can be directly read through the negative angle, the negative angle can be converted into the positive angle by utilizing an induction formula of the trigonometric function, and the sine value and the cosine value of the positive angle can be directly read in a trigonometric function teaching and learning demonstration instrument.
Similarly, when the angle values of the first swing arm 5 of the two demonstration instruments are changed to be α and 180 ° + α, respectively, the two demonstration instruments are used for teaching and learning, and the relationship between the α angle and the 180 ° + α angle can be demonstrated, that is, sin (180 ° + α) = -sin α, cos (180 ° + α) = -cos α, tan (180 ° + α) = tan α, and cot (180 ° + α) = cot α.
5) Demonstrating monotonicity and parity of sine functions and cosine functions:
the first swing arm 5 of the trigonometric function teaching and learning demonstration instrument shown in fig. 1-4 is rotated, and the monotonicity of the sine function is observed by observing the degree change on the second swing arm 6 and the positive and negative direction change on the longitudinal axis 2 of the linear rectangular coordinate system. It can be seen that in the first quadrant the sine value increases monotonically, in the second and third quadrants decreases monotonically, and in the fourth quadrant increases monotonically. The utility model discloses trigonometric function teaching and learning demonstration appearance can demonstrate the monotonicity of sinusoidal function directly perceivedly, can see out the sinusoidal function is the original point symmetry about rectangular coordinate system equally, demonstrates its parity;
the first swing arm 5 of the trigonometric function teaching learning demonstration instrument shown in fig. 1-4 is rotated, and monotonicity of a cosine function is observed by observing change of scale values on a horizontal axis 3 of a linear rectangular coordinate system and change of positive and negative directions on the horizontal axis 3 of the linear rectangular coordinate system. It can be seen that cosine values monotonically decrease in the first quadrant and the second quadrant of the cosine function, and cosine values monotonically increase in the third quadrant and the fourth quadrant. It can also be seen that the cosine function is symmetrical about the longitudinal axis 2 of the rectangular coordinate system of linear bars, demonstrating the parity thereof.
In addition, the utility model discloses a trigonometric function teaching learning demonstrates appearance can also demonstrate other trigonometric functions, no longer exemplifies one by one here.
The utility model discloses the inventor diminishes the trigonometric function teaching demonstration appearance of design before and simplifies, but on guaranteeing the basis of its original function, still refine the function, let the trigonometric function teaching demonstration appearance after the improvement not only teacher demonstrate on class and use as the teaching aid demonstration, the student also can one oneself demonstrate the transform of trigonometric function and calculate the trigonometric function value of various integer angles, still can hand-carry simultaneously, through the combination of theory and practice, improve the interest that the student studied the trigonometric function greatly.
The above description is only exemplary of the present invention, and is not intended to limit the scope of the present invention. For the components of the present invention can be mutually combined under the conflict-free condition, and any technical personnel in the field can make equivalent changes and modifications without departing from the concept and principle of the present invention, all belong to the protection scope of the present invention.
Claims (10)
1. The utility model provides a trigonometric function teaching study demonstration appearance which characterized in that, trigonometric function teaching study demonstration appearance includes: the swing arm mechanism comprises a bottom plate (1), wherein a linear rectangular coordinate system, a central shaft (4), a first swing arm (5) and a second swing arm (6) are arranged on the bottom plate (1), the central shaft (4) is arranged at the origin of the linear rectangular coordinate system and hinged to the bottom plate (1), one end of the first swing arm (5) is connected with the central shaft (4), the other end of the first swing arm (5) is hinged to the second swing arm (6), and the first swing arm (5) is connected between the bottom plate and the second swing arm (6);
the bottom plate (1) is provided with annular angle scale marks which represent the angle scale marks of the trigonometric function teaching and learning demonstration instrument;
the linear rectangular coordinate system comprises a linear rectangular coordinate system transverse axis (3) and a linear rectangular coordinate system longitudinal axis (2), and scale marks are arranged on the linear rectangular coordinate system transverse axis (3) and the linear rectangular coordinate system longitudinal axis (2);
and linear scale marks are uniformly distributed on the second swing arm from a hinge point to the other end of the second swing arm (6).
2. A trigonometric function teaching, learning and demonstrating device according to claim 1, wherein the scale marks on said second swing arm (6) are radiated to the other end of said second swing arm (6) with the hinge point of said second swing arm (6) with said first swing arm (5) as the zero point of the scale marks.
3. The trigonometric function teaching, learning and demonstrating instrument according to claim 1, wherein said second swing arm (6) is rectangular and straight, and one end of said second swing arm (6) is a hinged end, said hinged end is provided with a hinged point, and the other end of said second swing arm (6) is a free end.
4. The trigonometric function teaching, learning and demonstrating instrument according to claim 1, wherein said rectangular coordinates of linear axes (3) have uniformly distributed linear scale marks.
5. The trigonometric function teaching and learning demonstration instrument according to claim 1, wherein the longitudinal axis (2) of the rectangular linear coordinate system is evenly distributed with linear graduation marks.
6. The trigonometric function teaching and learning demonstration instrument according to claim 1, wherein the scale marks of the base plate (1), the scale marks of the second swing arm (6) and the scale marks of the rectangular coordinate system are protrusions or grooves.
7. The trigonometric function teaching and learning demonstration instrument according to claim 1, wherein the first swing arm (5) further comprises a first swing arm groove (7), and the first swing arm groove (7) connects the hinge point and the origin of the rectangular linear coordinate system.
8. A trigonometric function teaching and learning demonstration apparatus according to claim 1, wherein the base plate (1) is circular.
9. A trigonometric function teaching and learning demonstration apparatus according to claim 1, wherein said first swing arm (5) is rectangular and rectilinear.
10. A trigonometric function teaching and learning demonstration instrument according to claim 7, wherein said first swing arm groove (7) is elongated.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202222281874.1U CN218100499U (en) | 2022-08-29 | 2022-08-29 | Trigonometric function teaching and learning demonstration instrument |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202222281874.1U CN218100499U (en) | 2022-08-29 | 2022-08-29 | Trigonometric function teaching and learning demonstration instrument |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN218100499U true CN218100499U (en) | 2022-12-20 |
Family
ID=84449186
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202222281874.1U Active CN218100499U (en) | 2022-08-29 | 2022-08-29 | Trigonometric function teaching and learning demonstration instrument |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN218100499U (en) |
-
2022
- 2022-08-29 CN CN202222281874.1U patent/CN218100499U/en active Active
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN218100499U (en) | Trigonometric function teaching and learning demonstration instrument | |
| US3826021A (en) | Device for demonstrating and calculating trigonometric functions | |
| CN205468137U (en) | Mathematics plotter | |
| US6941667B2 (en) | Teaching sin and cosine instrument | |
| CN207140630U (en) | A kind of foldable multifunctional chi | |
| CN206030882U (en) | Multifunctional ruler and compass for teaching purpose | |
| US20140101952A1 (en) | Multi-Axis Educational Graphing Ruler | |
| CN201501217U (en) | Multi-functional plotting instrument | |
| CN203739491U (en) | Multifunctional drawing ruler | |
| CN210881464U (en) | Triangular compasses | |
| CN210293012U (en) | Trigonometric function teaching aid | |
| CN202189488U (en) | Multifunctional learning ruler | |
| KR100618031B1 (en) | multi-functional drafting device | |
| CN105150725A (en) | Multifunctional teaching aid for math class | |
| CN212708680U (en) | Multi-functional teaching aid that mathematical education used | |
| RU155986U1 (en) | DRAWING AND MEASURING TOOL | |
| CN206067321U (en) | A kind of mathematical education Geometric figure drawing special ruler | |
| CN210535117U (en) | Magic ruler for learning music | |
| CN214727759U (en) | Multifunctional teaching aid | |
| CN208351767U (en) | A kind of teaching determines instrument with position | |
| US20120003618A1 (en) | Geo-meter graph reader learning system | |
| CN211364088U (en) | Trigonometric function learning ruler | |
| CN203026006U (en) | Trigonometric function measuring instrument | |
| US3835298A (en) | Device for demonstrating and calculating mathematical functions | |
| CN2325809Y (en) | Sine function quick calculating rule |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| GR01 | Patent grant | ||
| GR01 | Patent grant |