NDA Math Mock Test 03 – Question 72

Question:

A square matrix A is called orthogonal if:

एक वर्ग आव्यूह A लंबकोणीय (orthogonal) कहलाता है यदि:

Options:

  • \(A = A^2\)
  • \(A^T = A^{-1}\)
  • \(A = A^{-1}\)
  • \(A = A^T\)
  • \(A = A^2\)
  • \(A^T = A^{-1}\)
  • \(A = A^{-1}\)
  • \(A = A^T\)

Correct Answer: b)

Explanation:

By definition, a square matrix \(A\) is orthogonal if:
\[A A^T = A^T A = I\]
Multiplying both sides by \(A^{-1}\) gives:
\[A^T = A^{-1}\]
Hence, the transpose of the matrix equals its inverse.
Hence, the correct option is (b).

परिभाषा के अनुसार, एक वर्ग आव्यूह A लंबकोणीय कहलाता है यदि:
\[A A^T = A^T A = I\]
जिसका अर्थ है कि इसका परिवर्त इसके व्युत्क्रम के बराबर होता है:
\[A^T = A^{-1}\]
अतः सही विकल्प (b) है।

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