Returns the arcsine of a number. The arcsine is the angle whose sine is number. The returned angle is given in radians in the range -p/2 to p/2.
Number is the sine of the angle you want and must be from -1 to 1.
To express the arcsine in degrees, multiply the result by 180/PI( ).
ASIN(-0.5) equals -0.5236 (-p/6 radians)
ASIN(-0.5)*180/PI() equals -30 (degrees)