Poem about Sine, Cosine, Tangent (trigonometric ratios in right triangles) for grade 9 students in Vietnam

Poem about Sine, Cosine, Tangent (trigonometric ratios in right triangles) for grade 9 students in Vietnam

1. Poem about Sine, Cosine, Tangent (trigonometric ratios in right triangles) for grade 9 students​

Sin: đi học (opposite side – hypotenuse)

Cos: không hư  (adjacent side – hypotenuse)

Tang: đoàn kết (opposite side – adjacent side)

Cotang: kết đoàn (adjacent side – opposite side)

Sao Đi Học (Sin = Opposite / Hypotenuse)

Cứ Khóc Hoài (Cos = Adjacent / Hypotenuse)

Thôi Đừng Khóc (Tan = Opposite / Adjacent)

Có Kẹo Đây (Cotan = Adjacent / Opposite)

2. Poem about Sum Formula regarding Sine, Cosine, Tangent 

Tan một tổng hai tầng cao rộng,

Trên thượng tầng tan cộng cùng tan,

Hạ tầng số 1 ngang tàng,

Dám trừ đi cả tan tan oai hùng.

3. Poem about Tripling Formula regarding Sine, Cosine, Tangent 

Nhân ba một góc bất kỳ

Sin thì ba bốn, cos thì bốn ba

Dấu trừ đặt giữa hai ta

Lập phương chỗ bốn thế là ok.

4. Poem about Half-Angle Formula (t = tg(a/2)) regarding Sine, Cosine, Tangent 

Sin, cos mẫu giống nhau chả khác,

Ai cũng là một cộng bình tê (1+t^2),

Sin thì tử có hai tê (2t),

Cos thì tử có một trừ bình tê (1-t^2).

5. Poem about The General Formula Regarding Deviation of Pi

Hơn kém bội hai pi sin, cos

Tang, cotang hơn kém bội pi.

Sin(a + k.2.180) = sin(a)

Cos(a + k.2.180) = cos(a)

Tg(a + k.180) = tg(a)

Cotg(a + k.180) = cotg(a)

6. Values of Trigonometric Functions for Special Angles

Cos đối, sin bù, phụ chéo, khác pi tan.

Cosin của hai góc đối bằng nhau;

Sin của hai góc bù nhau thì bằng nhau;

Phụ chéo là hai góc phụ nhau

Thì sin góc này = cos góc kia,

Tan góc này = cot góc kia;

Tan của hai góc hơn kém pi thì bằng nhau.

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Poem about Sine, Cosine, Tangent (trigonometric ratios in right triangles) for grade 9 students in Vietnam (Image from the Internet)

What are requirements to achieve regarding trigonometric ratios in right triangles for grade 9 Mathematics in Vietnam?

Based on the General Education Program for Mathematics issued together with Circular 32/2018/TT-BGDDT, the requirements to achieve regarding trigonometric ratios in right triangles for grade 9 Mathematics in Vietnam are as follows:

- Recognize the values of sin (sine), cos (cosine), tan (tangent), cot (cotangent) of an acute angle.

- Explain the trigonometric ratios of special acute angles (angles 30°, 45°, 60°) and of two complementary angles.

- Calculate the (exact or approximate) values of trigonometric ratios of an acute angle using a handheld calculator.

- Explain some relationships about the sides and angles in a right triangle (the length of a leg is equal to the hypotenuse times the sine of the opposite angle or the cosine of the adjacent angle; the length of a leg is equal to the other leg times the tangent of the opposite angle or the cotangent of the adjacent angle).

- Solve practical problems associated with the trigonometric ratios of an acute angle (e.g., calculating the length of line segments, measuring angles, and applying to solve right triangles, etc.).

What are the experiential activities in the grade 9 Mathematics program in Vietnam?

According to the General Education Program for Mathematics issued together with Circular 32/2018/TT-BGDDT, there are four experiential activities in the grade 9 mathematics program. Specifically, schools organize the following activities for students and may add other activities depending on the conditions:

Activity 1: Learning about some financial knowledge such as:

- Practicing making personal investment plans.

- Getting to know about insurance.

- Getting to know about growth problems (determining the investment capital to achieve the desired growth rate).

Activity 2: Practicing the application of mathematical knowledge to real life and interdisciplinary topics, such as:

- Applying knowledge of the system of linear equations with two unknowns in chemical equation balancing problems.

- Applying knowledge of probability in calculating the probability of offspring results from genetic crosses.

Activity 3: Organizing extracurricular activities such as hands-on activities outside the classroom, learning projects, math games, math competitions, such as:

- Applying trigonometric ratio knowledge in real life (e.g., measuring the distance between two positions where there is an obstruction or only one position is accessible).

- Applying formulas for area and volume in real-life measurement: measuring and calculating the area and volume of shapes within the school grounds related to cylinders, cones, and spheres.

- Searching for or practicing creating videos related to circles, right triangles, regular polygons, and rotations.

Activity 4 (if the school has the necessary conditions): Organizing exchanges with experts to understand more about the role of mathematics in real life and in various professions.