## Trigonometry 7th Edition

a. $\theta$ b. $\pi - \theta$ c. $\theta - \pi$ d. $2\pi - \theta$
RECALL: The reference angle $\hat{\theta}$ of an angle $\theta$, based on its terminal side's location, can be found using the following formulas: Quadrant I: $\hat{\theta}=\theta$ Quadrant II: $\hat{\theta} = \pi - \theta$ Quadrant III: $\hat{\theta} = \theta - \pi$ Quadrant IV: $\hat{\theta} = 2\pi - \theta$ Thus, the missing expressions are: a. $\theta$ b. $\pi - \theta$ c. $\theta - \pi$ d. $2\pi - \theta$