Question

cosA=2mn/m²+n², prove that cosecA= m²+n²/m²-n²​

Answer 1

cosA=2mn\m²+n²

now cosA = adjcent \ hypotaneos

so, 2mn is adjcent side and m²+n² is hypo.

Now we can find opposite side using Pythagoras theorem.

so opposite side is m²-n².

Now cosecA= hypo\opp

so, CosecA = m²+n²\m²-n².

Hence proved.

Answer 2

Here is the answer

see the pic attached