MCQ
If $A=\left[\begin{array}{cc}\cos \alpha & \sin \alpha \\ -\sin \alpha & \cos \alpha\end{array}\right]$, then $A^{10}=$
  • A
    $\left[\begin{array}{cc}\cos 10 \alpha & -\sin 10 \alpha \\ \sin 10 \alpha & \cos 10 \alpha\end{array}\right]$
  • $\left[\begin{array}{cc}\cos 10 \alpha & \sin 10 \alpha \\ -\sin 10 \alpha & \cos 10 \alpha\end{array}\right]$
  • C
    $\left[\begin{array}{cc}\cos 10 \alpha & \sin 10 \alpha \\ -\sin 10 \alpha & -\cos 10 \alpha\end{array}\right]$
  • D
    $\left[\begin{array}{cc}\cos 10 \alpha & -\sin 10 \alpha \\ -\sin 10 \alpha & -\cos 10 \alpha\end{array}\right]$

Answer

Correct option: B.
$\left[\begin{array}{cc}\cos 10 \alpha & \sin 10 \alpha \\ -\sin 10 \alpha & \cos 10 \alpha\end{array}\right]$
$\left[\begin{array}{cc}\cos 10 \alpha & \sin 10 \alpha \\ -\sin 10 \alpha & \cos 10 \alpha\end{array}\right]$

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