find sin x/2 if cos x= -5/8, with x terminating in Q2.?

Answer 1

sin^2 x/2 = (1/2)(1 - cosx)
sin^2 x/2 = (1/2)(1 + 5/8)
sin^2 x/2 = 13/16
sin x/2 = (1/4)√13