Question

Solve, for 0 ≤ θ < 360 , the equation
sin2 θ = 1 + cos θ

Answer 1

θ = 90°, 180°, or 270°

Explanation:

sin²θ = 1 + cos θ

Use Pythagorean identity.

1 − cos²θ = 1 + cos θ

Move everything to one side and simplify.

0 = cos²θ + cos θ

Factor.

0 = cos θ (cos θ + 1)

Solve.

cos θ = 0 or -1

θ = 90°, 180°, or 270°