Find the integrals of the functions.
∫cos2x−cos2αcosx−cosαdx.
∫cos2x−cos2αcosx−cosαdx=∫(2cos2x−1)−(2cos2α−1)(cosx−cosα)dx(∴cos2x=2cos2x−1)
=∫2cos2x−1−2cos2α+1(cosx−cosα)dx=∫2(cos2x−cos2α)(cosx−cosα)dx
=2∫(cosx−cosα)(cosx+cosα)(cosx−cosα)dx|∴a2−b2=(a+b)(a−b)|
=2[∫cosxdx+cosα∫1dx]=2[sinx+cosα.x]+C=2sinx+2xcosα+C