If a line has direction ratios 2, −1, −2, then its direction cosines are:
If a line has direction ratios 2, −1, −2, then its direction cosines are:
- A. 2/3, −1/3, −2/3
- B. 2/9, −1/9, −2/9
- C. 2, −1, −2
- D. 1/3, −1/3, −2/3
Answer: A) 2/3, −1/3, −2/3
Explanation: Magnitude = √(2² + (−1)² + (−2)²) = √(4 + 1 + 4) = 3. Dividing DRs by 3 gives DCs: 2/3, −1/3, −2/3.
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