Explanation:
sin = -3/5 we are told this is between pi/2 and 3pi/2
so Quadrant II and III
of these two quadrants
sin is only negative in Q III where cos is also negative
TRIG IDENTITY: sin^2 + cos^2 = 1 will show cos = - 4/5
TRIG IDENTITY : Sin (2Φ) = 2 sinΦ cosΦ
= 2 (-3/5) (-4/5) = 24/25 = .960