A function which returns, in radians, the arc sine of its numeric argument. The permitted range of the argument is –1 to +1.
By convention, the result will be in the range –PI/2 to +PI/2 (–90 to +90 degrees).
If you know the sine of the angle, this function will tell you the angle (in radians). Unfortunately, you cannot do this with complete certainty because one sine has two associated angles (see ACS for details).
In the example below, radian_angle becomes equal to the angle (in radians) whose sine is y.
You can convert the answer to degrees by using the DEG function (the DEG function is equivalent to multiplying by 180/PI). The example below is similar to the first one, but the angle is in degrees.