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📐 Mathematics  ·  Introduction to Three Dimensional Geometry  ·  JEE

The reflection of the point (1, 2, 3) in the xy-plane is:

Answer: (1, 2, −3).

  • A (1, 2, −3)
  • B (−1, −2, 3)
  • C (1, −2, 3)
  • D (−1, 2, 3)

Correct answer: A. (1, 2, −3)

Explanation: Reflection in the xy-plane negates the z-coordinate, giving (1, 2, −3).

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 →