Решите уравнение
сos2x-cos6x=0

Решениесos2x-cos6x=02*(sin4x)*(sin3x) = 0sin4x = 0 4x = πn, n∈Zx = 1/4*(πn), n∈Zsin3x = 03x = πk, k∈Zx =(1/3)* πk, k∈Z