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📐 Mathematics  ·  Introduction to Three Dimensional Geometry  ·  JEE

Three points are collinear in space if and only if:

Answer: The largest of the three pairwise distances equals the sum of the other two.

  • A They lie in the same octant of the coordinate system
  • B The largest of the three pairwise distances equals the sum of the other two
  • C All three pairwise distances are equal to one another
  • D Their coordinates sum to zero in each of the three components

Correct answer: B. The largest of the three pairwise distances equals the sum of the other two

Explanation: Collinearity forces one point to lie between the others, so the longest distance is exactly the sum of the two shorter ones.

zxyOP(x, y, z)first octant:x>0, y>0, z>0

Concept context

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

Read the full Introduction to Three Dimensional Geometry notes →