#### Answer

$$θ=\frac{5\pi }{4}+2\pi n,\:θ=\frac{7\pi }{4}+2\pi n$$

#### Work Step by Step

Solving the equation using inverse trigonometric functions, we find:
$$\sin \left(θ\right)=-\frac{\sqrt{2}}{2} \\ θ=\frac{5\pi }{4}+2\pi n,\:θ=\frac{7\pi }{4}+2\pi n$$