Question

cosx+cos^2x=1/2-sin^2x срочнооо плиз

Answer 1

sinx*cosx*cos2x*cos4x=1/8*cosx
1/2sin2xcos2xcos4x=1/8cosx
1/4sin4xcos4x=1/8cosx
1/8sin8x=1/8cosx
sin8x-cosx=0
sin8x-sin(П/2-x)=0
2sin(4,5x-П/4)cos(3,5x+П/4)=0
9/2x-П/4=Пk  9/2x=П/4+Пk  x=П/18+2Пk/9
П/4+7/2x=П/2+Пk
7/2x=П/4+Пk
x=П/14+2Пk/7

Answer 2

$\\ cosx+ cos^{2} x= \frac{1}{2} - sin^{2} x \\ cosx+cos^{2} x+sin^{2} x= \frac{1}{2} \\ cosx+1= \frac{1}{2} \\ cosx=- \frac{1}{2}$
по таблице брадиса -  x=120.