Is (1+sin beta)/(cos beta) equivalent to (cos^2 beta)/(cos beta- cos beta sin beta)

To answer your question, yes, they are equivalent, since

Similar manipulations and simplifications will show that A, B, and D are all equivalent to the starting expression, so the answer would be C.

answer: all of the odd numbers were opened

the first person was the one that was opening all of the lockers. since one is odd, this causes all of the odd number lockers to be opened in the end.