If the inital side of is along the positive x-axis and the terminal side includes the point P given below, find in radians:
(a) , =?
(b) , ?
(c) , ?
(d) , ?
(e) , ?
(f) , ?
When calculating the value of theta, you begin with the positive x-axis 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 $\displaystyle cos x = - cos (\pi - x), sin x = sin(\pi - x)$.