## Precalculus (6th Edition) Blitzer

$\approx 0.78$
RECALL: The following are the means on how to find the reference angle of an angle $\theta$ based on its position: (1) Quadrant I: $\theta$ (itself) (2) Quadrant II: $\pi-\theta$ (3) Quadrant III: $\theta - \pi$ (4) Quadrant IV: $2\pi-\theta$ The angle $\theta = 5.5$ is between $\frac{3\pi}{2}\approx 4.71$ and $2\pi \approx 6.28$. This means that the angle is in in Quadrant IV. Use formula (4) to obtain: reference angle of $5.5$ is $2\pi - 5.5 \approx 0.78$