Definition: The Greek letter, $\sin$, appears in mathematics but does not have a direct equivalent in Latin. It refers to circular arcs or measurements from 0 to $\pi$ radians. In geometry, it represents an angle formed by two line segments intersecting at their endpoints. $\arcsin(x)$ is the inverse of $\arccos(x)$. It calculates the angle whose sine is $x$. For example, $\arcsin(1/2)$ represents the angle with a sine of 1/2 radians.