### Home > A2C > Chapter 12 > Lesson 12.1.3 > Problem 12-55

12-55.

Solve each equation for

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 = ?