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Prove the following identities: (cotA-cosecA)2=1-cosA1+cosA

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Question

Prove the following identities:

`(cotA - cosecA)^2 = (1 - cosA)/(1 + cosA)`

Sum
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Solution

`(cotA - cosecA)^2 = (1 - cosA)/(1 + cosA)`

`cot^2A - 2cotA cosecA + cosec^2x = (1 - cosA)/(1 + cosA)`

`(cos^2A)/(sin^2A) - (2cosA)/(sin^2A) + 1/(sin^2A) = (1 - cosA)/(1 + cosA)`

`(cos^2A - 2cosA + 1)/(sin^2A) = (1 - cosA)/(1 + cosA)`

`(cos^2A - 2cosA + 1)/(1 - cos^2A) = (1 - cosA)/(1 + cosA)`

`((1 - cosA)(1 - cosA))/((1 + cosA)(1 - cosA)) = (1 - cosA)/(1 + cosA)`

`(1 - cosA)/(1 + cosA) = (1 - cosA)/(1 + cosA)`

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Chapter 21: Trigonometrical Identities - Exercise 21 (A) [Page 325]

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Selina Concise Mathematics [English] Class 10 ICSE
Chapter 21 Trigonometrical Identities
Exercise 21 (A) | Q 31. | Page 325
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