Question

Решите уравнение
cos x*cos 3x=sin 3x*sin x

Answer 1

cjsxcos3x-sin3xsinx=0
cos(3x+x)=0
cos4x=0
4x=π/2+πn
x=π/8+πn/4,n∈z

Answer 2

=2462764=246.276.4=.0