Question

2cos(x-11П/2)cosx=sinx

Answer 1

$2cos (x- frac{11 pi }{2} )cos x=sin x \ -2sin xcos x=sin x \ -2sin xcos x-sin x=0 \ -sin x(2cos x+1)=0 \ left[begin{array}{ccc}sin x=0\ cos x=- frac{1}{2} end{array}rightto left[begin{array}{ccc}x_1=pi k, k in Z\ x_2=pm frac{2 pi }{3}+2 pi n,n in Z end{array}right$