Symmetry and Periodicity of Trigonometric Functions Practice Test

Using the periodicity property of cosine, $\cos(\theta+2\pi)=\cos(\theta)$, what is $\cos\left(\frac{13\pi}{6}\right)$?​

If $\sin\left(\frac{\pi}{6}\right)=\frac{1}{2}$, then using the odd symmetry of sine, what is $\sin\left(-\frac{\pi}{6}\right)$?