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Mathematics · 2026 · 2 marks
CBSE 2026 · Region 2 · Set 2 · Q22 (b)
Prove that: 1+(cot^2 α)/(1+ cosec α)= cosec α
Prove that : \[1+\frac{\cot ^{2} \alpha}{1+\operatorname{cosec} \alpha}=\operatorname{cosec} \alpha \]
Marking-scheme solution
LHS \(\displaystyle =1+\frac{\cot ^{2} \alpha}{1+\operatorname{cosec} \alpha}\)
\(\displaystyle =1+\frac{(\operatorname{cosec} \alpha+1)(\operatorname{cosec} \alpha-1)}{(1+\operatorname{cosec} \alpha)}\)
\(\displaystyle =1+\operatorname{cosec} \alpha-1\)
\(\displaystyle =\operatorname{cosec} \alpha=\) RHS
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CBSE Class 10 Mathematics past-paper question from the 2026 board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.