Answer
$\frac{3\pi}{8}, \frac{7\pi}{8},\frac{11\pi}{8},\frac{15\pi}{8} $
Work Step by Step
$tan(2\theta)=-1 \longrightarrow 2\theta=\pi-\frac{\pi}{4}, 2\pi-\frac{\pi}{4}, \pi+\pi-\frac{\pi}{4}, \pi+2\pi-\frac{\pi}{4}, 2\pi+\pi-\frac{\pi}{4}, 2\pi+2\pi-\frac{\pi}{4}, \longrightarrow \theta=\frac{3\pi}{8}, \frac{7\pi}{8},\frac{11\pi}{8},\frac{15\pi}{8} $
