Trigonometric function plays an important role in studying the properties of geometric shapes such as triangles and circles, and is also a basic mathematical tool for studying periodic phenomena. In mathematical analysis, trigonometric function is also defined as the solution of infinite series or specific differential equation, which allows its value to be extended to any real value or even complex value.
Common trigonometric functions
Common trigonometric functions are sine function, cosine function and tangent function. In navigation, surveying, engineering and other disciplines, such as cotangent function, secant function, cotangent function, orthovector function and cotangent function will also be used.
Other trigonometric functions, such as semi-orthogonal vector function and semi-cofactor function. The relationship between different trigonometric functions can be obtained by geometric intuition or calculation, which is called trigonometric identity.