Question

prove that cosx+cosy/cosy-cosx

Answer 1

Answer:

We know that cos A + cos B = [2{cos (A-B)/2}.{cos ( A+B)/2}] ••••••(1)

And cos A- cos B= 2[{Sin(A-B)/2}.{Sin(A +B)/2}] ••••••(2)

therefore (1) / (2) = cot ( A-B)/2 .cot (A+B)/2