Answer: Averaging all four position vectors, dividing each coordinate sum by 4.
- A Averaging only three vertices and ignoring the fourth
- B Taking the midpoint of the longest edge in every case
- C Projecting the triangle centroid of ABC onto the fourth vertex
- D Averaging all four position vectors, dividing each coordinate sum by 4
Correct answer: D. Averaging all four position vectors, dividing each coordinate sum by 4
Explanation: The centroid of n points is the arithmetic mean of their coordinates, so for a tetrahedron each coordinate sum is divided by 4.
Concept context
Coordinate axes and planes in space, octants, distance between two points, and the section formula
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