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महाराष्ट्र राज्य शिक्षण मंडळएस.एस.सी (इंग्रजी माध्यम) इयत्ता १० वी

Prove that (cosθ)/(1 + sinθ) = (1 – sinθ)/(cosθ).

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प्रश्न

Prove that `(cosθ)/(1 + sinθ) = (1 - sinθ)/(cosθ)`.

सिद्धांत
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उत्तर

L.H.S. = `(cosθ)/(1 + sinθ)`

= `(cosθ)/(1 + sinθ) xx (1 - sinθ)/(1 - sinθ)`   ...[On rationalising the denominator]

= `(cosθ(1 - sinθ))/(1 - sin^2θ)`

= `(cosθ(1 - sinθ))/(cos^2θ)`   ...`[(∵ sin^2θ + cos^2θ = 1),(∴ 1 -sin^2θ = cos^2θ)]`

= `(1 - sinθ)/(cosθ)`

= R.H.S.

∴ `(cosθ)/(1 + sinθ) = (1 - sinθ)/(cosθ)`

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पाठ 6: Trigonometry - Exercise

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