📐 Mathematics · Introduction to Three Dimensional Geometry · JEE

If the midpoint of the segment joining (a, 2, 3) and (5, b, 7) is (3, 4, 5), then a + b equals:

Answer: 7.

Correct answer: A. 7

Explanation: (a + 5)/2 = 3 gives a = 1; (2 + b)/2 = 4 gives b = 6. So a + b = 7.

Concept context

Coordinate axes and planes in space, octants, distance between two points, and the section formula