# Question: hi with prep 3 and 4 im wondering why they...

###### Question details

Hi, with Prep 3 and 4 I'm wondering why they don't use the 2nd reference angle 7pi/12 but instead where do they get the -5pi/12 for their 2nd answer? Kind of the same with Prep 4... i can get the pi/4 but not sure about the rest of the answer. The answers for Prep 3 is $-\frac{5\mathrm{\pi}}{12}+n\mathrm{\pi},\frac{5\mathrm{\pi}}{12}+n\mathrm{\pi}$ and for Prep 4 it is $\frac{\mathrm{\pi}}{4}+\frac{\mathrm{n\pi}}{3}$

thanks very much, Michael