InterviewSolution
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If \(\rm m = \left[ \begin{array}{cc} 2 &0\\ 0&1\end{array}\right] and \ n= \left[ \begin{array}{cc} 0 &1\\ -2&0\end{array}\right]\) then what is the value of the determinant of m sinθ + n cosθ 1. 12. -13. 34. 2 |
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Answer» Correct Answer - Option 4 : 2 Calculation: m sinθ + n cosθ = sin θ \(\rm \left[ \begin{array}{cc} 2 &0\\ 0&1\end{array}\right]\) + cos θ \(\rm \left[ \begin{array}{cc} 0 &1\\ -2&0\end{array}\right]\) = \(\rm \left[ \begin{array}{cc} 2\sin θ &0\\ 0&\sin θ\end{array}\right]\)+\(\rm \left[ \begin{array}{cc} 0 &\cosθ\\ -2\cosθ&0\end{array}\right]\) = \(\rm \left[\begin{array}{cc} 2\sin θ &\cos θ\\ -2\cos θ&\sin θ\end{array}\right]\) Now, |m sinθ + n cosθ| = \(\rm \left| \begin{array}{cc} 2\sin θ &\cos θ\\ -2\cos θ&\sin θ\end{array}\right|\) = \(2\sin^2\theta \) + \(\rm 2 cos^2\theta \) = 2(\(\sin ^2 \theta +\cos^2\theta \)) = 2 Hence, option (4) is correct. |
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