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प्रश्न
Prove the following identities, where the angles involved are acute angles for which the expressions are defined:
`(cosec θ – cot θ)^2 = (1-cos theta)/(1 + cos theta)`
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उत्तर
L.H.S
= `(cosec θ – cot θ)^2`
= `(1/sintheta - costheta/sintheta)^2`
= `(1-costheta)^2/(sin^2 theta)`
= `(1-cos theta)^2/(1-cos^2theta)`
= `((1-costheta)(1-costheta))/((1-costheta)(1+cos theta)) `
= `(1-cos theta)/(1+costheta)`
= R.H.S
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Activity:
L.H.S. = `square`
= `square/(sinθ) + (sinθ)/(cosθ)`
= `(cos^2θ + sin^2θ)/square`
= `1/(sinθ.cosθ)` ...`[cos^2θ + sin^2θ = square]`
= `1/(sinθ) xx 1/square`
= `square`
= R.H.S.
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Activity: L.H.S. = cotθ + tanθ
= `cosθ/sinθ + square/cosθ`
= `(square + sin^2theta)/(sinθ xx cosθ)`
= `1/(sinθ xx cosθ)` ....... ∵ `square`
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= `square xx secθ`
∴ L.H.S. = R.H.S.
