Answer
$\frac{\pi}{4},\frac{3\pi}{4},\frac{5\pi}{4},\frac{7\pi}{4}$
Work Step by Step
From $ sin^2\theta=cos^2\theta $, we have $ sin^2\theta=1-sin^2\theta $ and thus $ sin^2\theta=\frac{1}{2}$.
This leads to $ sin\theta=\frac{\sqrt 2}{2}$ and $ sin\theta=-\frac{\sqrt 2}{2}$.
Within $[0,2\pi]$, the solutions are: $\theta=\frac{\pi}{4},\frac{3\pi}{4},\frac{5\pi}{4},\frac{7\pi}{4}$
