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Q) Prove that: 1 + \frac{(\cot^2 \alpha)}{(1 + \cos ec \alpha)} = cosec α

(Q 22 B – 30/2/2 – CBSE 2026 Question Paper)

Ans: 

Let’s start from LHS:

LHS = 1 + \frac{(\cot^2 \alpha)}{(1 + \cos ec \alpha)}

Step 1: From Trigonometric identities, we know that

1 + cot 2 α = cosec 2 α

∴ cot 2 α = cosec 2 α – 1

Step 2: Let’s substitute the value of cot 2 α from stel 1:

LHS = 1 + \frac{(\cot^2 \alpha)}{(1 + \cos ec \alpha)}

= 1 + \frac{(\cos ec^2 \alpha - 1)}{(1 + \cos ec \alpha)}

= 1 + \frac{(\cos ec \alpha - 1)(\cos ec \alpha + 1)}{(1 + \cos ec \alpha)}

= 1 + \frac{(\cos ec \alpha - 1)\cancel{(\cos ec \alpha + 1)}}{\cancel{(\cos ec \alpha + 1)}}

= 1 + (cosec α – 1)

= cosec α = RHS

Hence Proved !

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