Solve each equation for 0° ≤ θ < 360°. Homework Help ✎
2sinθ = −1
cos2θ + 5cosθ + 4 = 0
Now use what you remember about the unit circle to solve for θ. Remember that there may be more than one solution.
Treat cosθ as you would x and factor. Now set the factors equal to zero. Note that instead of having x = something, you will have cosθ = something.
If cosθ = −1, θ = ?