Trigonometric functions are of type numeric. Trigonometry deals with the relationships among the sides of a triangle and its angles. An angle can be measured in degrees, radians or Gon (grad). Since a computer usually generates trigonometric values by series approximation, the angle is specified in radians when used as the argument to the SIN, COS, and TAN functions or as the returned value from the ASIN, ACOS, and ATAN functions.

A radian is an arc of a circle whose length is equal to the circle's radius. Since the relationship between a circle's radius and circumference is `C = 2 * P * r`, and there are 360 degrees in a circle, we can derive from

1 radian = 180/P = 57.295780 degrees 1 degree = P/180 = 0.01745329 radians.

Another scale that is sometimes used to measure angles is Gon, also known as grad. The values for conversion are:

1 radian = 200/P = 63.661977 Gon (grad) 1 Gon (grad) = P/200 = 0.01570796 radians.