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Prove that: (cosecA-sinA)(secA-cosA)=1tanA+cotA - Mathematics

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Question

Prove that:

`(cosecA - sinA)(secA - cosA) = 1/(tanA + cotA)`

Sum

Solution

L.H.S. = `(cosecA - sinA)(secA - cosA)`

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

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

= `(cos^2A/sinA)(sin^2A/cosA)`

= sin A cos A

R.H.S. = `1/(tanA + cotA)`

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

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

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

= `(sinAcosA)/1`

= sin A cos A

∴ L.H.S. = R.H.S.

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Chapter 21: Trigonometrical Identities - Exercise 21 (B) [Page 327]

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Selina Mathematics [English] Class 10 ICSE
Chapter 21 Trigonometrical Identities
Exercise 21 (B) | Q 1.7 | Page 327
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