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Prove that: sinA+cosAsinA-cosA+sinA-cosAsinA+cosA=22sin2A-1 - Mathematics

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Question

Prove that:

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

Sum
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Solution

LHS = `(sin A + cos A)/(sin A - cos A) + (sin A - cos A)/(sin A + cos A)`

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

=  `(sin^2 A + cos^2 A + 2 sin Acos A + sin^2 A + cos^2 A - 2sin A. cos A)/(sin^2 A - cos^2 A)`

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

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

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

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

= RHS

Hence proved.

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