CPM Homework Help : CCA2 Problem 7-90

Calculate the value of each expression below. Give an exact measurement, if possible. Each measure is given in radians.

$\sin(4)$
Hint (a):
Make sure your calculator is in radian mode.
Answer (a):
$−0.76$

$\sin(\frac{4\pi}{3})$
Hint (b):
Since $\frac{4\pi}{3}$ is related to the $30^{^{\circ}}-60^{^{\circ}}-90^{^{\circ}}$ angles, this one has an exact answer. Locate it on the unit circle. Notice that it will be a reflection (twice) of $\sin\left(\frac{\pi}{3}\right)$ .
More Help (b):
It is in the third quadrant.