Question

use the fact that there are 2pi radians in each circle to find another angle,smaller than 2pi,that is equivalent to 13pi/4

Answer 1

$\dfrac{13\pi}4\equiv\dfrac\pi4\mod2\pi$

Or, put another way, since $\dfrac{13\pi}4=2\pi+\dfrac\pi4$, it follows that $\dfrac\pi4$ is an equivalent angle.

Answer 2

Answer:

Step-by-step explanation:

Given is an angle $\frac{13\pi}{4}$

We know that there are 2pi radians in each circle

Hence after crossing 2pi radians, the values repeat

$\frac{13\pi}{4}=2\pi+\frac{5\pi}{4}$

Hence equivalent angle is

$\frac{5\pi}{4}$

i.e. in the III quadrant making pi/4 with negative x axis.