The SIN function accepts a number that indicates the number of radians in an angle and returns the sine of that angle. SIN(x) is always between -1 and 1 inclusive. The angle is first reduced to lie between 0 and pi/2, by means of the following identities:

SIN(-x) = -SIN(x)
SIN(2*N*pi + x) = SIN(x)
SIN(pi + x) = -SIN(pi - x)
SIN(pi/2 + x) = SIN(pi/2 - x) 

The final calculation is one of two polynomial approximations, depending on the value of the reduced argument.