Please explain this question

Dear Student,

f o r m i n i m u m d e v i a t i o n, r_{1} = r_{2} A l s o r_{1} + r_{2} = A S o, r_{1} = r_{2} = \frac{A}{2} = \frac{60 °}{2} = 30 ° I t i s i n d e p e n d e n t o f t h e r a y, s o b o t h w i l l h a v e s a m e a n g l e o f r e f r a c t i o n i . e . 30 °

Regards,