Im coding in console app, and i can't seem to find a way to get the inverse of sine.

I need it to evaluate:

a = sin^-1(0.2/0.5)

a=23.58 degrees

but while looking through the different 'Math.' options i didn't find anything like or would resemble equivalent to the inverse of sin (sin^-1). Ive also checked the help search and tried to do it another alternative but was required to get the inverse of tan and am stuck.

Could someone help me out?