Step-by-step explanation:
Not sure where you are in your studies, so I do not know which method is desired to solve this problem ....here is the easiest way:
find the angles
sin a = .438
a = arcsin (.438) = 25.97634°
b = arcsin (.297) = 17.27750°
then sin (a+b) = sin ( 25.97634 + 17.27750) = .685
