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प्रश्न
Prove that `(1 + sintheta)/(1 - sin theta)` = (sec θ + tan θ)2
उत्तर
L.H.S = `(1 + sintheta)/(1 - sin theta)`
= `((1 + sintheta)/(costheta))/((1 - sintheta)/(costheta))` ......[Dividing numerator and denominator by cos θ]
= `(1/costheta + (sintheta)/(costheta))/(1/costheta - (sintheta)/(costheta)`
= `(sectheta + tantheta)/(sectheta - tantheta)`
= `(sectheta + tantheta)/(sectheta - tantheta) xx (sectheta + tantheta)/(sectheta + tantheta)` ......[On rationalising the denominator]
= `(sectheta + tantheta)^2/(sec^2theta - tan^2theta)`
= `(sectheta + tantheta)^2/1` ......`[(because 1 + tan^2theta = sec^2theta),(therefore sec^2theta - tan^2theta = 1)]`
= (sec θ + tan θ)2
= R.H.S
∴ `(1 + sintheta)/(1 - sin theta)` = (sec θ + tan θ)2
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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
