
Finding Theta?

When calculating the value of theta, you begin with the positive xaxis and move counterclockwise. If you know a little bit of trigonometry, these are all straightforward. Recall that $\displaystyle cos \frac{\pi}{4} = sin \frac{\pi}{4} = \frac{\sqrt{2}}{2}$, and the identities $\displaystyle cos x =  cos (\pi  x), sin x = sin(\pi  x)$.

Most of those answers are some form of $\displaystyle \frac{\pi}{2} \mbox{ or } \frac{\pi}{4}$.
For example b. is $\displaystyle \frac{3\pi}{4}$.
You show us some work on the others.