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Prove the following identities: (1+tan2A)+(1+1tan2A)=1sin2A-sin4A

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Question

Prove the following identities:

`(1 + tan^2 "A") + (1 + 1/tan^2"A") = 1/(sin^2 "A" - sin^4"A")`

Sum
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Solution

L.H.S. = `(1 + tan^2 "A") + (1 + 1/tan^2"A")`

= (sec2A) + (1 + cot2A)

= sec2A + cosec2A

= `1/cos^2"A" + 1/sin^2"A"`

= `(sin^2"A" + cos^2"A")/(sin^2"A" cos^2"A")`

= `1/(sin^2 "A" cos^2"A")`

= `1/(sin^2"A"(1 - sin^2"A")`

= `1/(sin^2"A" - sin^4"A")`

= R.H.S.

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Chapter 2: Trigonometry - 1 - EXERCISE 2.2 [Page 31]

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