Answer
a. $\frac{5\pi}{3}$.
b. See figure.
c. $\frac{\pi}{3}$
Work Step by Step
a. Given the angle $\frac{11\pi}{3}=\frac{6\pi+5\pi}{3}=2\pi+\frac{5\pi}{3}$, we see that the positive angle that is less than $ 2\pi$ and is co-terminal with the given angle is $\frac{5\pi}{3}$.
b. See figure.
c. The reference angle can be found as $2\pi-\frac{5\pi}{3}=\frac{\pi}{3}$ (angle with respect to the x-axis)
