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If A is orthogonal (A A^T = I), then |A| =
A|A|²
B2
C±1
D0
Answer & Solution
Correct answer: C. ±1
|A A^T| = |I| = 1. But |A A^T| = |A| × |A^T| = |A|². So |A|² = 1 → |A| = ±1. Det +1: proper rotation. Det -1: improper (rotation × reflection).
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