1.

Prove that : \(\frac{1}{cosec θ- cot θ}\) = (cosecθ + cotθ).

Answer»

L.H.S = \(\frac{1}{cosec θ+ cot θ}\) = \(\frac{cosec\theta+cot\theta}{(cosecθ − cotθ)(cosecθ + cotθ)}\) 

(By multiplying numerator and denominator by cosecθ + cotθ) 

= \(\frac{cosecθ + cotθ}{cosec^2θ − cot^2θ}\) (∵ (a+b)(a–b) = a2 − b2

= \(\frac{cosecθ + cotθ }{1}\) = cosecθ + cotθ = R.H.S. 

(∵ cosec2θ = 1 + cot2θ ⇒ cosec2θ − cot2θ = 1

Hence proved



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