Question

Помогите решить
2cos^2x=2cos(п/2+x)

Answer 1

$2cos^2x=2cosleft(fracpi2+xright)\cos^2x=-sin x\1-sin^2x=-sin x\sin^2x-sin x-1=0\sin x=t,;sin^2x=t^2,;tin[-1;;1]\t^2-t-1=0\D=1+4=5\t_1=frac{1-sqrt5}2\t_2=frac{1+sqrt5}2 textgreater 1;-;He;nogx.\sin x=frac{1-sqrt5}2\x=(-1)^ncdotarcsinleft(frac{1-sqrt5}2right)+pi n,;ninmathbb{Z}$