Answer
$\frac{\pi}{2},\frac{3\pi}{2}$
Work Step by Step
Step 1. Solve to get $sin\theta=\pm1$
Step 2. For $sin\theta=1$, we have $\theta=\frac{\pi}{2}$
Step 3. For $sin\theta=-1$, we have $\theta=\frac{3\pi}{2}$
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