If a line lies in the xy-plane and makes an angle of 30° with the positive x-axis, its direction cosines are:
If a line lies in the xy-plane and makes an angle of 30° with the positive x-axis, its direction cosines are:
- A. √3/2, 1/2, 0
- B. 1/2, √3/2, 0
- C. √3/2, 0, 1/2
- D. 0, √3/2, 1/2
Answer: A) √3/2, 1/2, 0
Explanation: Since it lies in the xy-plane, it makes 90° with the z-axis (n = cos 90° = 0). It makes 30° with x-axis (l = cos 30° = √3/2) and 60° with y-axis (m = cos 60° = 1/2).
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