## Calculus (3rd Edition)

$\dfrac{\pi}{4}, \dfrac{5\pi}{4}$
Since $\tan{\theta} = \dfrac{\cos{\theta}}{\sin{\theta}}$ As $\tan{\theta} = 1$, we search figure 22 for points where $\cos{\theta} = \sin{\theta}$ The two angles on the unit circle where $\cos{\theta} = \sin{\theta}$ are $\dfrac{\pi}{4}$ and $\dfrac{5\pi}{4}$ $\theta = \dfrac{\pi}{4}, \dfrac{5\pi}{4}$