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प्रश्न
Prove that cosec θ – cot θ = `sin theta/(1 + cos theta)`
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उत्तर
L.H.S = cosec θ – cot θ
= `1/sintheta - costheta/sintheta`
= `(1 -costheta)/sintheta`
= `(1 - costheta)/sintheta xx (1 + costheta)/(1 +costheta)` .....[On rationalising the numerator]
= `(1 - cos^2theta)/(sintheta(1 +costheta))`
= `(sin^2theta)/(sintheta(1 + costheta))` .....`[(because sin^2theta + cos^2theta = 1),(therefore 1 - cos^2theta = sin^2theta)]`
= `sintheta/(1 + costheta)`
= R.H.S
∴ cosec θ – cot θ = `sin theta/(1 + cos theta)`
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Solution :
L.H.S. = cotθ + tanθ
= `cosθ/sinθ + sinθ/cosθ`
= `(square + square)/(sinθ xx cosθ)`
= `1/(sinθ xx cosθ)` ............... `square`
= `1/sinθ xx 1/square`
= cosecθ × secθ
L.H.S. = R.H.S
∴ cotθ + tanθ = cosecθ × secθ
