1, formula 1: Let α be any angle, and the values of the same trigonometric function of the angles with the same terminal edges are equal.

sin(2kπ+α)=sinα(k∈Z).

cos(2kπ+α)=cosα(k∈Z).

tan(2kπ+α)=tanα(k∈Z).

cot(2kπ+α)=cotα(k∈Z).

2. Formula 2: Let α be an arbitrary angle, and the relationship between the trigonometric function value of π+α and the trigonometric function value of α.

sin(π+α)=-sinα.

cos(π+α)=-cosα.

tan(π+α)=tanα.

cot(π+α)=cotα.

Related applications of trigonometric functions;

The knowledge of triangles is widely used in measurement, navigation, geometry, physics and so on. If the shell associated with actual production and life in each application problem is taken out, the essence of solving the triangle problem is exposed.

It is necessary to improve the ability of analyzing and solving problems and turn practical problems into abstract mathematical problems. Everyone is required to master the method of solving oblique triangle by sine and cosine theorem, make clear the extensive application of knowledge of solving oblique triangle in practice, master the transformation from practical problems to solving oblique triangle types, and gradually improve the application ability of mathematical knowledge.

The above contents refer to Baidu Encyclopedia-Trigonometric Function.