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NDA 2018
Exam
NDA
Year
2018
Subject
Mathematics
Chapter
Matrices

NDA 2018 · Mathematics · Matrices

A square matrix A is called orthogonal if

A square matrix AA is called orthogonal if

Options

  1. AA=A2\mathrm{A}=\mathrm{A}^2
  2. BA′=A−1\mathrm{A}^{\prime}=\mathrm{A}^{-1}
  3. CA=A−1\mathrm{A}=\mathrm{A}^{-1}
  4. DA=A′\mathrm{A}=\mathrm{A}^{\prime}

Correct answer

B. A′=A−1\mathrm{A}^{\prime}=\mathrm{A}^{-1}

Step-by-step solution

If A−1=AT\mathrm{A}^{-1}=\mathrm{A}^{\mathrm{T}}, then A is orthogonal matrix.
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