Question

Write two angles coterminal to 5pi/7, one that’s positive and one that’s negative

Answer 1

As given by the question

There are given that the angle:

$\frac{5\pi}{7}$

Now,

To find a positive and negative coterminal angle, add and subtract 2pi to the given angle.

Then,

$\begin{gathered} \frac{5\pi}{7}+2\pi=\frac{5\pi+14\pi}{7} \\ =\frac{19\pi}{7} \end{gathered}$

And,

$\begin{gathered} \frac{5\pi}{7}-2\pi=\frac{5\pi-14\pi}{7} \\ =\frac{-9\pi}{7} \end{gathered}$

Hence, the positive and negative angles are shown below:

$\frac{19\pi}{7}\text{ and -}\frac{9\pi}{7}$