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Question
Prove that cosec θ – cot θ = `sin theta/(1 + cos theta)`
Solution
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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Activity:
L.H.S = `square`
= `square (1 - (sin^2theta)/(tan^2theta))`
= `tan^2theta (1 - square/((sin^2theta)/(cos^2theta)))`
= `tan^2theta (1 - (sin^2theta)/1 xx (cos^2theta)/square)`
= `tan^2theta (1 - square)`
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= R.H.S
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