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Question
Prove the following identity :
`(1 + sinθ)/(cosecθ - cotθ) - (1 - sinθ)/(cosecθ + cotθ) = 2(1 + cotθ)`
Solution
LHS = `(1 + sinθ)/(cosecθ - cotθ) - (1 - sinθ)/(cosecθ + cotθ)`
= `((1 + sinθ)(cosecθ + cotθ) - (1 - sinθ)(cosecθ - cotθ))/(cosec^2θ - cot^2θ)`
= `(cosecθ + cotθ + 1 + cosθ - cosecθ + cotθ + 1 - cosθ)/(1 + cot^2θ - cot^2θ)` (∵ `cosec^2θ = 1 + cot^2θ`)
= 2 + 2cotθ = 2(1 + cotθ)
Notes
θ
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