Help find arcsin(3/5) and (1/sqrt5)

Question

Hello!
Do you know how to get the value of arcsin(3/5) and arcsin(1/sqrt5) in terms of pi radian?

Answer 1

sin^-1 ( 3/ 5 ) = 0.6 435

You should express radians in ratio of pi

     Sin^-1 ( 3/5 ) = (0.6435/pi ) pi = 0. 2225 pi = pi/5

arcsin( 1/ √5 ) = 0.14758361765043*pi = 3pi/20 radians.