NCERT Mathematics, Class 11, textbook pages 208–216

How to help your child with Class 11 Maths Chapter 11, Introduction to Three Dimensional Geometry, at home

Coordinates in 3D and distance, explained for parents: a 45-minute study session, a quick challenge, a 5-day plan and the mistakes to watch for.

yzx(x, y, z)

NCERT Class 11 Maths Chapter 11 Introduction to Three Dimensional Geometry: what it teaches

Your teen extends coordinates to three axes, locates points in octants, and uses the distance formula in space.

Why it matters later. 3D geometry continues in Class 12 with vectors and lines in space.

See it: this chapter in pictures

(−2, 3, −1)signs (−, +, −)one of 8 octants
Signs place the point.
(1,2,3) to (4,6,3)√(9 + 16 + 0)= 5
Add the z term.
z-axis points: (0, 0, z)xy-plane: z = 0three coordinate planes
Zeros show position.

You need

  • a room corner as axes
  • a ruler
  • cardboard

Tonight’s 45 minutes

  1. Use a room corner as origin: floor edges as x and y, vertical edge as z. Give a ceiling-light position.
  2. Plot (2, 3, 4) with a sketch.
  3. Find the octant of (−2, 3, −1).
  4. Find the distance between (1, 2, 3) and (4, 6, 3) (5).

Words to use

  • x-, y-, z-axis
  • octant
  • coordinates in space
  • distance formula

Watch for

  • Mixing axes order. Always (x, y, z).
  • Forgetting the z term in distance. √(Δx² + Δy² + Δz²).

What it sounds like at home

A short example of the conversation. Your words will differ; the questions are what matter.

YouWhere is the ceiling light?

Your childAbout (2, 3, 2.8) in metres.

A game for this week: Room coordinates

  1. Choose a room corner as origin.
  2. Measure positions of objects.
  3. Write coordinates.
  4. Others locate objects from coordinates.

A 5-day plan, 45 minutes a day

  1. Day 1Explain-back.
  2. Day 2Worked examples.
  3. Day 3Practice set.
  4. Day 4Real-life problem.
  5. Day 5Mixed quiz.

Everyday moments to practise

  • Drone positions.
  • 3D printing.
  • Game design.
  • Architecture.

Quick check

Ask these at the end of the week. Tap to see the answer.

Number of octants?

8.

Distance (1,2,3) to (4,6,3)?

5.

Coordinates of a point on the z-axis?

(0, 0, z).

Ready for the next chapter when your child…

  • Plots points in 3D.
  • Identifies octants.
  • Uses the 3D distance formula.

Activities, wording and illustrations are Mathify Kids’ own, following the topics of NCERT’s Mathematics (Class 11). See the full Class 11 parent guide for every chapter.

Questions parents ask

How many coordinate planes are there?

Three: xy, yz and zx.

What is an octant?

One of eight regions divided by the planes.

Is the section formula included?

It may be reduced in the current syllabus; check.