Simplify (double angle formulas)
a) cos3xcos2x + sin3xsin2x
b) 2cos^2 pi/6 - 1
c) 1 - 2sin^2 pi/12
(a) sin(a+b) = sina cosb + cosa sinb
(b) cos2θ = 2cos^2θ - 1
(c) cos2θ = 1 - 2sin^2θ
Looks like you just need to review your basic formulas