Помогите решить

1) cos+sin (pi/2+x) = 1

2) tg^2x+tgx=0

3) 5-4sin^2x=4cosx

1) cosx+sin (pi/2+x) = 1

cosx+cosx=1

2cosx=1

cosx=1/2

x=+-π/3+2πn, n∈z

2) tg^2x+tgx=0

tgx (tgx+1) = 0

tgx=0⇒x=πn, n∈z

tgx=-1⇒x=-π/4+πk, k∈z

3) 5-4sin^2x=4cosx

5-4+4cos²x-4cosx=0

4cos²x-4cosx+1=0

(2cosx-1) ²=0

2cosx=1

cosx=1/2

x=+-π/3+2πn, n∈z