JEE Main 2025 Mathematics question
Let A = . If for some θ ∈ (0, π), , then the sum of the diagonal elements of the matrix is equal to .
Answer: 6
Solution
A is orthogonal, A²==, so A³=I. Trace of expression = Tr(2A³) = Tr(2I) = 6
Let A = . If for some θ ∈ (0, π), , then the sum of the diagonal elements of the matrix is equal to .
A is orthogonal, A²==, so A³=I. Trace of expression = Tr(2A³) = Tr(2I) = 6