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Prove the Following Identity : 1 Cos a + Sin a − 1 + 2 Cos a + Sin a + 1 = Cos E C a + Sec a - Mathematics

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Question

Prove the following identity : 

`1/(cosA + sinA - 1) + 2/(cosA + sinA + 1) = cosecA + secA`

Sum

Solution

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

 = `(cosA + sinA + 1 + cosA + sinA - 1)/((cosA + sinA)^2 -1)`

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

= `(2(cosA + sinA))/(1 + 2cosAsinA - 1) = (cosA + sinA)/(cosAsinA)`

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

= `1/sinA + 1/cosA`

= cosecA + secA

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Chapter 21: Trigonometric Identities - Exercise 21.1

APPEARS IN

Frank Mathematics - Part 2 [English] Class 10 ICSE
Chapter 21 Trigonometric Identities
Exercise 21.1 | Q 5.1
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