Question

1. sinθ = -1

Explanation:

Step1: Recall sine function properties

The sine function has a range of $[-1,1]$, with $\sin\theta=-1$ at $\theta=\frac{3\pi}{2}+2k\pi$ ($k\in\mathbb{Z}$).

Answer:

$\theta = \frac{3\pi}{2} + 2k\pi$ for any integer $k$