Question 286551
Since {{{pi<5pi/4<3pi/2}}}, this means that {{{5pi/4}}} is in the 3rd quadrant. If you draw out the angle along with its associated triangle, you'll see that the reference angle is the angle that is closest to the origin. Since {{{pi}}} is the closest known angle, and {{{5pi/4>pi}}}, we know that we have to subtract {{{pi}}} from this angle to find the reference angle.



So {{{5pi/4-pi=5pi/4-4pi/4=(5pi-4pi)/4=pi/4}}} which means that the reference angle is {{{pi/4}}}