Question

Cos^2X-sinX*cosX=0 Помогите!

Answer 1

$cos^{2}x-sinx*cosx=0 (1- sin^{2}x)-sinx*cosx=0 1- sin^{2}x-sinx*cosx=0 /:cos^{2}x; \frac{1}{cos^{2}x}-tg^{2}x-tgx=0; (1+tg^{2}x)-tg^{2}x-tgx=0 1+tg^{2}x-tg^{2}x+tgx=0 1+tgx=0 tgx=(-1) x=arctg(-1)+ \pi n.. .; x=- \frac{ \pi }{4}+ \pi n$