Question

Cos(3п/2 + х) - 5cosx = 0

Answer 1

cos(3π/2+x)-5cosx=0
sinx-5cosx=0 |:cosx≠0
sinx/cosx-5*(cosx/cosx)=0
tgx-5=0
tgx=5
x=arctg5+πn, n∈Z