Take a right triangle as an example: SIN (sine) is the ratio of the opposite side (the side opposite to the angle) to the hypotenuse (the longest side), and COS (cosine) is the ratio of the adjacent side (the adjacent short side) to the hypotenuse (the longest side) of an angle in a triangle.
(formulas of trigonometric functions):
1, trigonometric function introduction:
Trigonometric function is a transcendental function in elementary functions in mathematics. Their essence is the mapping between any set of angles and a set of ratio variables. The usual trigonometric function is defined in a plane rectangular coordinate system. Its definition field is the whole real number field. The other is defined in a right triangle, but it is incomplete. Modern mathematics describes them as the limit of infinite sequence and the solution of differential equation, and extends their definitions to complex system.
2. Inductive formula:
Formula 1: Let α be an arbitrary angle, and the values of the same trigonometric functions with the same terminal angles are equal:
Equation 2: Let α be an arbitrary angle, and the relationship between π+α and the trigonometric function value of α:
Equation 3: Relationship between any angle-α and trigonometric function value of α:
Equation 4: Relationship between π-α and trigonometric function value of α:
Equation 5: Relationship between 2π-α and trigonometric function value of α:
Equation 6:? And the relationship with the trigonometric function value of α;