Question

the exact value of sin13pi/8 is?

Answer 1

\[\frac{13\pi}{8}=\frac{1}{2}\left(\frac{13\pi}{4}\right)\]

Answer 2

you will need this identity
\[\sin\left(\frac{1}{2}A\right)=\pm \sqrt{\frac{1-\cos A}{2}}\]
choose the sign that corresponds to the the sine function on the quadrant where \(13\pi/8\) lies