Question

Find cos(2theta) if cos(theta)= 3/4

Answer 1

Sin theta = 8/17 and theta is in the second quadrant. Find sin(2theta),cos(2theta),tan(2theta) exactly sin(2theta) cos(2theta) tan(2theta) sin(2theta) would it be 2 x (8/17) cos(2theta) would be 2 x (15/17) tan(2theta) would be 2 x (8/17 divided by 15/17) is this correct?