Question

Преобразуйте в произведение

Answer 1

$cos2 alpha + cos14 alpha + cos6 alpha + cos10 alpha =$$2*cos frac{14 alpha +2 alpha }{2} cosfrac{14 alpha -2 alpha }{2} +2*cosfrac{10 alpha +6 alpha }{2} cosfrac{10alpha -6alpha }{2} =$$2cos8 alpha *cos6 alpha +2cos8 alpha *cos2 alpha =2cos8 alpha (cos6 alpha +cos2 alpha )=$$2cos8 alpha *2cos frac{6 alpha +2 alpha }{2} cos frac{6 alpha -2 alpha }{2} =4cos8 alpha *cos4 alpha *cos2 alpha$