In mathematics, the inverse trigonometric functions(occasionally called cyclometric functions) are the inverse functions of the trigonometric functions (with suitably restricted domains). Specifically, they are the inverses of thesine, cosine, tangent, cotangent, secant, and cosecantfunctions.
Sine, in mathematics, is a trigonometric function of an angle. The sine of an angle is defined in the context of a right triangle: for the specified angle, it is the ratio of the length of the side that is opposite that angle (that is not the hypotenuse) to the length of the longest side of the triangle (i.e., the hypotenuse).
Trigonometric functions are commonly defined as ratios of two sides of a right triangle containing the angle, and can equivalently be defined as the lengths of various line segments from a unit circle. More modern definitions express them as infinite series or as solutions of certain differential equations, allowing their extension to arbitrary positive and negative values and even to complex numbers.
On the web2.0 calculator for this website, if you want to find the inverse sine of a value, you would type in "Arcsin". It would be the same for other trignometric functions (ex. Arccos, Arctan etc.).
Also hate to call you out KitKat.. but you kinda just copied and pasted from Wikipedia. Good stuff though, very helpful information