Answer: Solving the three equations obtained by equating squared distances pairwise.
- A Averaging the four vertices, which always gives the required point
- B Taking the midpoint of the longest edge of the tetrahedron
- C Projecting the centroid onto the XY-plane in every case
- D Solving the three equations obtained by equating squared distances pairwise
Correct answer: D. Solving the three equations obtained by equating squared distances pairwise
Explanation: Equating squared distances pairwise removes the quadratic terms and leaves three linear equations in x, y and z - the circumcentre generally differs from the centroid.
Concept context
Coordinate axes and planes in space, octants, distance between two points, and the section formula
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