The three fundamental trigonometric functions, sine, cosine and tangent, are not one-to-one. However, we can restrict their domains to intervals on which they are one-to-one. The restricted functions have inverses, written [math]sin^{-1}x[/math], [math]cos^{-1}x[/math], and [math]tan^{-1}x[/math]. These inverses are also known as arcsin, arccos, and arctan.