Question

solve this question as fast as possible please

Answer 1

cot²A - cot²B = (sin²B - sin²A)/(sin²A.sin²B)
L.H.S = cot²A - cot²B 
= (cosec²A -1) - ( cosec²B -1)                                       ∵ cot²Ф = cosec²Ф - 1
= cosec²A -1 - cosec²B + 1 =  cosec²A - cosec²B
= 1/sin²A  - 1/sin²B
=  (sin²B - sin²A)/(sin²A.sin²B) 
= R.H.S

Answer 2

This is the answer. Hope it is easier way if solving the question