Q32 / 55 · NEST (NISER) 2012 · Mathematics

$\left(\begin{array}{cc}\cot \theta & -1 \\ 1 & \cot \theta\end{array}\right)\left(\begin{array}{cc}\cot \theta & 1 \\ -1 & \cot \theta\end{array}\right)^{-1}=\left(\begin{array}{cc}\alpha & -\beta \\ \beta & \alpha\end{array}\right)$ then

  • A
    $\alpha=1$ and $\beta=1$.
  • B
    $\alpha=1$ and $\beta=0$
  • Correct answer
    C
    $\alpha=\cos 2 \theta$ and $\beta=\sin 2 \theta$.
  • D
    $\alpha=\cos \theta$ and $\beta=\sin \theta$.

Hence, the correct answer is option: 'C'.

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