The minimum positive period sum of the function y = cos (3 π / 2-x) cosx is

The minimum positive period sum of the function y = cos (3 π / 2-x) cosx is

y=cos(3π/2-x)cosx
=-sinxcosx
=-(1/2)sin2x,
Period T = 2 π / 2 = π,
The range is [- 1 / 2,1 / 2]