CBSE 2026 · Region 5 · Set 1 · Q21 · 2 marks
Evaluate $\displaystyle \sin \left[\tan ^{-1} \tan \left(\frac{3 \pi}{4}\right)\right]$.
Marking-scheme solution
Given expression $\displaystyle =\sin\left[\tan^{-1}(-1)\right]$ or $\displaystyle \sin\left[\tan^{-1} \tan\left(\pi-\dfrac{\pi}{4}\right)\right]$
$\displaystyle =\sin\left(-\dfrac{\pi}{4}\right)$
$\displaystyle =-\dfrac{1}{\sqrt{2}}$
Inverse Trigonometric FunctionsProperties of Inverse Trigonometric FunctionsApplyvery_short_answermedium
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CBSE Class 12 Mathematics past-paper question from the 2026board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.