You mean sin and inverse sin functions. Almost every computer has a calculator.
In Windows it's in star>all programs>accessories>calculator.
Under the view menu, check scientific.
sin (cos and tan) are in a column towards the left.
You can perform these functions in degrees, radians or grads (i've never used grads for anything - i think civil engineers use it.)
Type a number, like 30, click sin, get 0.5.
To get the inverse, click the inv check box towards the top on the left. The click sin. Read 30.
In Ubuntu Linux, it's under accessories. Look for scientific.
The calculator is more command like - so you issue sin first, then the number, then =.
For some reason, knoppix doesn't seem to have it.
On the Mac, it's an accessory.