Question

Reference number for 5/8 pi

Answer 1

reference angles are between 0 and pi/2
5pi/8 is in quadrant 2 so ref angle = pi - 5pi/8 = 3pi/8

Answer 2

\[\frac{ 5\pi }{ 8 }?\]

Answer 3

link to unit circle
study it , use it as a reference for these type of questions

http://en.wikipedia.org/wiki/File:Unit_circle_angles_color.svg