Answer: The perpendicular from the point meets the axis at the foot sharing that axis coordinate, so that coordinate contributes nothing.
- A Distances in space are always computed pairwise between two coordinates only
- B The third coordinate is always zero for points measured from an axis
- C The perpendicular from the point meets the axis at the foot sharing that axis coordinate, so that coordinate contributes nothing
- D Every axis lies in the XY-plane, making the third coordinate irrelevant
Correct answer: C. The perpendicular from the point meets the axis at the foot sharing that axis coordinate, so that coordinate contributes nothing
Explanation: The foot of the perpendicular from P to the x-axis is (x, 0, 0), so the difference in the x-coordinate is zero and only y and z survive in the formula.
Concept context
Coordinate axes and planes in space, octants, distance between two points, and the section formula
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