In mathematics, the inverse trigonometric function, sometimes called arcus function, inverse function or circular metric function, is the inverse function of trigonometric function (with appropriate restrictions). ?

Specifically, they are the inverse functions of sine, cosine, tangent, cotangent, secant and auxiliary functions, and are used to get an angle from the triangle ratio of any angle. Inverse trigonometric functions are widely used in engineering, navigation, physics and geometry.

Extended data

Obey the rules—

1, in order to ensure that the function corresponds to the single value of the independent variable, the determined interval must be monotonous;

2. The function is preferably continuous in this interval (the reason why it is best here is because the arctangent and the anti-cotangent functions are discontinuous);

3. For the convenience of research, it is often required that the selected interval includes the angle from 0 to π/2;

4. Make sure that the function value domain on the interval should be the same as the definition domain of the whole function. The inverse trigonometric function thus determined is single-valued. In order to distinguish it from the multi-valued inverse trigonometric function above, the notation of a in arc is often changed to a, for example, the single-valued arcsine function is recorded as arcsin X.