Im stuck on a few questions...

Any ideas?

1) Solve the following equation for θ in the interval 0 ≤ θ ≤ 2π.

sin( 2 θ) +5/9 cos( θ) = 0

2) Solve

4 cos( 2 θ) = 1+tan( θ)

for θ in the interval −π/2 < θ < π/2.

3) Which of the following is equal to

(sin θ + cos θ)^2 + (sin θ − cos θ)^2 for all θ?

A) 2 cos(2 θ)

B) 2

C) 2 sin^2θ

D) cos(2 θ) − sin(2 θ)

E) 2 sin(2 θ)