JEE Mains · Maths · STD 12 - 3 and 4 . metrices and determinant
Let \(A=\left[\begin{array}{ccc}\cos \theta & 0 & -\sin \theta \\ 0 & 1 & 0 \\ \sin \theta & 0 & \cos \theta\end{array}\right]\). If for some \(\theta \in(0, \pi)\), \(A^2=A^T\), then the sum of the diagonal elements of the matrix \((\mathrm{A}+\mathrm{I})^3+(\mathrm{A}-\mathrm{I})^3-6 \mathrm{~A}\) is equal to _____ .
- A 6
- B 8
- C 10
- D 12
Answer & Solution
Correct Answer
(A) 6
Step-by-step Solution
Detailed explanation
\(\because \mathrm{A}\) is orthogonal matrix…
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