Dear Aspirant,
I have check the question it is misprint but I have tried to prove the Result hope this will help you.
here is the your answer:
recall your half-angle formula: tan(x/2) = sinx/(1+cosx) Now, we have 1+sec2A = (1+cos2A)/cos2A = 1/[cos2A/(1+cos2A)] = 1/[sin2A/(1+cos2A) * cos2A/sin2A] = 1/(tanA cot2A) = tan2A/tanA ---------------- (1) Now we can see that 1+sec4A = tan4A/tan2A--------------------(2)
now we multiply eq.1 and 2, we get
(1+sec2A)(1+sec4A) = cot A*tanA
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