Question

Упростите 1-2sin^2a+cos2a

Answer 1

$1-2sin^{2} alpha +cos2 alpha =sin^{2} alpha +cos^{2} alpha -2sin^{2} alpha +cos^{2} alpha -sin^{2} alpha = \ 2cos^{2} alpha -2sin^{2} alpha =2(cos^{2} alpha -sin^{2} alpha)=2 cos2 alpha$