The sine (sin), cosine (cos) and tangent (tan), cotangent (cot), secant (sec) and cotangent (csc) of acute angle A are all called the sales figures of acute angle triangle draft.

The definition method of acute trigonometric function value in junior high school learning is defined in the right triangle, so the calculation of acute trigonometric function value in junior high school is completed by constructing an imaginary right triangle, that is, putting this angle in the right triangle, the acute trigonometric function can be expressed as:

Sine is equal to the hypotenuse of the opposite side; Sina = account

Cosine (cos) is equal to the ratio of adjacent side to hypotenuse; cosA=b/c

Tangent (tan) is equal to the opposite side of the adjacent side; tanA=a/b

Cotangent (cot) is equal to the edge comparison of adjacent keys; cotA=b/a

In high school, coordinate definition method is used to solve the trigonometric function value, and then the angle is extended to any angle. The so-called acute trigonometric function is: what we learned in junior high school is acute trigonometric function.

Change:

The values of 1. acute trigonometric functions are all positive values.

2. When the angle changes from 0 to 90,

Sine value increases (or decreases) with the increase (or decrease) of angle, and cosine value decreases (or increases) with the increase (or decrease) of angle;

Tangent value increases (or decreases) with the increase (or decrease) of angle, and cotangent value decreases (or increases) with the increase (or decrease) of angle;

Secant value increases (or decreases) with the increase (or decrease) of angle, and cotangent value decreases (or increases) with the increase (or decrease) of angle.

3. When the angle changes between 0 ≤ A ≤ 90, 0 ≤ Sina ≤ 1, 0 ≤ COSA ≤1; When the angle is 0 0.

Triangle:

Triangle is a closed figure composed of three line segments on the same plane but not on the same straight line, which has applications in mathematics and architecture.

Ordinary triangles are divided into ordinary triangles (three sides are unequal) and isosceles triangles (isosceles triangles with unequal waist and bottom and isosceles triangles with equal waist and bottom, that is, equilateral triangles); According to the angle, there are right triangle, acute triangle and obtuse triangle, among which acute triangle and obtuse triangle are collectively called oblique triangle.