solve t when y =0.5

Y=0.9sin(pi/2 t)

0.5=0.9sin(pi/2 t)

0.5/0.9=sin (pi/2 t)

0.555=sin (pi/2 t)***** is it ok to move the pi/2 to left side??? was wondering coz its in brackets!

0.555/(pi/2)=sin t

0.3536=sin

sin inverse 0.3536 =t

0.36=t

can some one tell me if i did this right sorry i dont have the answer sheet.