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Question
Prove that `(1 + sintheta)/(1 - sin theta)` = (sec θ + tan θ)2
Solution
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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