Question

Решите 2 уравнения с обьяснением

1+cos8x = cos4x
sin 4x + 2cos^2 x = 1

Answer 1

Ответ:

1+cos8x=1+cos2*4x=2cos^2 4x

2cos^2 4x=2cos4x

2cos^2 4x-2cos4x=0

cos4x(c0s4x-1)=0

cos4x=0 4x=pi/2+pi n x=pi/8+1/4pi n

cos4x=1 4x=2pi k x=1/2pi k, n,keZ