Решить. sin^3x-7sinx•cos^2x+6 cos^3x=0

Sin³x-7sinxcos²x+6cos³x=0 (cos³x≠0)
tg³x-7tgx+6=0
tgx=y
y³-7y+6=0
(y-1)(y-2)(y+3)=0
y₁=1;y₂=2;y₃=-3
1) tgx=1;x=π/4+πn,n∈Z
2) tgx=2;x=arctg2+πk,k∈Z
3) tgx=-3;x=-arctg3+πm,m∈Z