Show that cos 2alpha = 2 sin^2beta + 4 cos (alpha + beta) sinalphasinbeta + cos 2 (alpha + beta) .
Evaluate : int ( cos 2x - cos 2alpha)( cos x - cosalpha) dx
a×sin alpha=b cos alpha show that a cos 2alpha+b sin 2 alpha=a - Brainly.in
If a denotes cos 2alpha + i sin 2alpha , with similar expression for b, c, d prove that a + b = 2 cos(alpha - beta) [cos(alpha + beta) + i sin(alpha + beta)]