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Question
Prove the following identity :
`(secA - 1)/(secA + 1) = (1 - cosA)/(1 + cosA)`
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Solution
LHS = `(secA - 1)/(secA + 1) = (1/cosA - 1)/(1/cosA + 1)`
= `(1 -cosA)/(1 + cosA) = "RHS"`
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