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CBSE Class 12 Math 2026 All Sets Solved Paper

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Question : 5 of 20
Marks: +1, -0
One of the values of x for which ∣cos⁡xsin⁡x−cos⁡xsin⁡x∣=1\begin{vmatrix} \cos x & \sin x \\ -\cos x & \sin x \end{vmatrix}=1 is
Solution:  
∣cos⁡xsin⁡x−cos⁡xsin⁡x∣=1\begin{vmatrix} \cos x & \sin x \\ -\cos x & \sin x \end{vmatrix}=1
⇒cos⁡xsin⁡x+cos⁡xsin⁡x=1\Rightarrow \cos x \sin x+\cos x \sin x=1
⇒2cos⁡xsin⁡x=1\Rightarrow 2 \cos x \sin x=1
⇒sin⁡2x=1\Rightarrow \sin 2x=1
⇒2x=π2\Rightarrow 2x = \frac{\pi}{2}
⇒x=π4\Rightarrow x = \frac{\pi}{4}
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