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Prove the following identities: cosecAcosecA-1+cosecAcosecA+1=2sec2A - Mathematics

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प्रश्न

Prove the following identities:

`(cosecA)/(cosecA - 1) + (cosecA)/(cosecA + 1) = 2sec^2A`

योग

उत्तर

L.H.S. `=(cosec A)/(cosecA - 1) + (cosecA)/(cosecA + 1)`

= `(cosec A (cosec A + 1) + cosec A (cosec A - 1))/((cosec A - 1) (cosec A + 1))`

= `(cosec^2 A+cosec  A + cosec^2 A-cosec  A)/((cosec A)^2 - (1)^2)`

= `(2 cosec^2 A)/(cosec^2 A - 1)`

= `(2 cosec^2 A)/(cot^2 A)`    ...(∵ cosec2 A – 1 = cot2 A)

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

= `2/cos^2A`

= 2 sec2 A

= R.H.S.

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अध्याय 21: Trigonometrical Identities - Exercise 21 (A) [पृष्ठ ३२४]

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सेलिना Mathematics [English] Class 10 ICSE
अध्याय 21 Trigonometrical Identities
Exercise 21 (A) | Q 25 | पृष्ठ ३२४
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