Mathematics
Prove the following identities :
sec4 A (1 - sin4 A) - 2 tan2 A = 1
Trigonometric Identities
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Answer
Solving L.H.S. of the above equation :
⇒ sec4 A (1 - sin4 A) - 2 tan2 A
⇒ sec4 A (1 - sin2 A)(1 + sin2 A) - 2 tan2 A
By formula,
1 - sin2 A = cos2 A
⇒ sec4 A cos2 A (1 + sin2 A) - 2 tan2 A
⇒ sec4 A (1 + sin2 A) - 2 tan2 A
⇒ sec2 A (1 + sin2 A) - 2 tan2 A
⇒ sec2 A + sec2 A sin2 A - 2 tan2 A
⇒ sec2 A + sin2 A - 2 tan2 A
⇒ sec2 A + tan2 A - 2 tan2 A
⇒ sec2 A - tan2 A
⇒ 1.
Since, L.H.S. = R.H.S.
Hence, proved that sec4 A (1 - sin4 A) - 2 tan2 A = 1.
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