Sin^2*x+9cos^2*x=5sin2x

sin^2*x+9cos^2*x=5(2sinx*cosx) sin^2*x+9cos^2*x-10sinx*cosx=0 (sin^2*x)/cos^2*x+(9cos^2*x)/cos^2*x-(10sinx*cosx)/cos^2*x=0 tg^2*x+9-10tgx=0 Пусть tgx=t t^2+9-10t=0 D= 100-36=64 x 1 и 2 =(10+-8)/2=9 и 1 tgx=9     and     tgx=1 x= arctg9+пиk              and         x=пи/4+пиN