Notice that
![(11\pi)/(6)=\left((6+5)/(6)\right))\pi=\pi+(5\pi)/(6)=\pi+(3\pi)/(6)+(2\pi)/(6)=\pi+(\pi)/(2)+(\pi)/(3)](https://img.qammunity.org/2023/formulas/mathematics/college/4yi5po3gurimaox3iminfjkym9aspqip4y.png)
Then, angle 11pi/6 terminates within quadrant 4. As for its reference angle, notice that pi/3 radians is equivalent to 60°; then,
Thus, the reference angle is equal to
![\text{ reference angle}=(\pi)/(2)-(\pi)/(3)=(\pi)/(6)=30\degree](https://img.qammunity.org/2023/formulas/mathematics/college/5nltibb8rqvag6p4v7eu1wzjebokoaohyz.png)
The reference angle of 11pi/6 is 30°.
Regarding angle 4pi/3, notice that
![(4\pi)/(3)=(\left(3+1\right))/(3)\pi=\pi+(\pi)/(3)=180\degree+60\degree=240\degree](https://img.qammunity.org/2023/formulas/mathematics/college/oxmhnq0qmlshpnsqsxub7o0mkpiusre6f1.png)
Then, 4pi/3 radians is equal to 240°