[Roai]

if i have sin x how do i find the x?

[RajatPawar]

The function asin( value ) returns the inverse of sin. (principle value only)

So, asin( sin( 90 * 3.14/180 ) ) would return Pi/2 (90 * 3.14/180)

Also, SINE and SINUS are two different things!

[Vince]

In almost all other languages that English it's called 'sinus'. Hence the mistake.