The SIN function returns the sine of an angle provided in radians. In geometric terms, the sine of an angle returns the ratio of a right triangle's opposite side over its hypotenuse. For example, the sine of PI()/6 radians (30°) returns the ratio 0.5.
The graph of sine, shown above, visualizes the output of the function for all angles from 0 to a full rotation. The function is periodic, so after a full rotation, the output of the function repeats. Geometrically, the function returns the y-component of the point corresponding to an angle on the unit circle. The function's output will always be in the range [-1, 1].