Question

Помогите!
1-2cosα+cos2α=

Answer 1

1-2cosα+cos2α=1-2cosα+cos^2α-sin^2α=2cos^2α+2cosα=2cosα(cosα+1)

Answer 2

$1-2cos alpha +cos^{2} alpha= sin^{2}alpha+cos^{2} alpha +2cos alpha +sin^{2}alpha-cos^{2} alpha= \ cos^{2} alpha + 2cos alpha$ 
вроде так