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Mathematics · 2026 · 1 mark
CBSE 2026 · Region 5 · Set 2 · Q1
If A = [sin θ, cos θ; - cos θ, sin θ] and A + A^′= I, then θ is equal to:
If $\displaystyle \mathrm{A}=\left[\begin{array}{cc}\sin \theta & \cos \theta \\ -\cos \theta & \sin \theta\end{array}\right]$ and $\displaystyle \mathrm{A}+\mathrm{A}^{\prime}=\mathrm{I}$, then $\displaystyle \theta$ is equal to :
Official answer
(B)
$\displaystyle \frac{\pi}{6}$
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CBSE Class 12 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.