Express 13 pi/6 as a function of an angle in quadrant i

For this case, the first thing you should do is to know the following transformation:
 pi radians = 180 degrees
 Applying the transformation we have:
 (13pi / 6) * (180 / pi) = 390 degrees
 Then, in quadrant 1 we have:
 390 - 360 = 30 degrees
 
 13 pi / 6 as a function of an angle in quadrant i is:
 30 degrees