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Prove that 1 1 + Cos ( 90 ∘ − a ) + 1 1 − Cos ( 90 ∘ − a ) = 2 Cos E C 2 ( 90 ∘ − a ) - Mathematics

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Question

prove that `1/(1 + cos(90^circ - A)) + 1/(1 - cos(90^circ - A)) = 2cosec^2(90^circ - A)`

Sum

Solution

LHS = `1/(1 + cos(90^circ - A)) + 1/(1 - cos(90^circ - A))`

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

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

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

= `2/cos^2A`

= `2sec^2A = 2cosec^2(90^circ - A)`

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Chapter 21: Trigonometric Identities - Exercise 21.3

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Frank Mathematics - Part 2 [English] Class 10 ICSE
Chapter 21 Trigonometric Identities
Exercise 21.3 | Q 10
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