Maths · Direction ratios and direction cosines and the angle between two intersecting lines
The number of straight lines that are equally inclined to the threedimensional c
The number of straight lines that are equally inclined to the threedimensional coordinate axes, is
- A. 2
- B. 4
- C. 6 \)
- D. 8
Step-by-step solution
A line equally inclined to the axes has direction cosines with equal absolute values: |l| = |m| = |n| = 1/√3. There are 2^3 = 8 sign combinations for (l, m, n), but opposite directions (sign flips) represent the same line, so distinct lines = 8/2 = 4.
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