**NCERT
Solutions for Class 11 Maths Chapter 12 Introduction to Three Dimensional
Geometry Ex 12.1**

NCERT Solutions for Class 11 Maths Chapter 12 Introduction to
Three Dimensional Geometry Ex 12.1 are the part of NCERT Solutions for Class 11
Maths. Here you can find the NCERT Solutions for Class 11 Maths Chapter 12
Introduction to Three Dimensional Geometry Ex 12.1.

**Ex 12.1 Class 11 Maths Question 1.**

A point is on the x-axis. What are its y-coordinates and z-coordinates?

**Solution:**

In three-dimensional geometry, the coordinates of any point on the x-axis are
of the form (x, 0, 0). Thus, the y-coordinate and the z-coordinate of the given
point is zero (0).

**Ex 12.1 Class 11 Maths Question
2.**

A point is in the XZ-plane. What can you say about its y-coordinate?

**Solution:**

In three-dimensional geometry, the coordinates of any point in XZ-plane are of
the form (x, 0, z). Thus, the y-coordinate of the given point is zero (0).

**Ex 12.1 Class 11
Maths Question 3.**

Name the octants in which the following points lie:(1, 2, 3), (4, -2, 3), (4, -2, -5), (4, 2, -5), (-4, 2, -5), (-4, 2, 5), (-3, -1, 6), (-2, -4, -7)

**Solution:**

The point (1, 2, 3) lies in Octant I.

The point (4, -2, 3) lies in Octant IV.

The point (4, -2, -5) lies in Octant VIII.

The point (4, 2, -5) lies in Octant V.

The point (-4, 2, -5) lies in Octant VI.

The point (-4, 2, 5) lies in Octant II.

The point (-3, -1, 6) lies in Octant III.

The point (-2, -4, -7) lies in Octant VII.

**Ex 12.1 Class 11
Maths Question 4.**

**Fill in the blanks:**

**(i)**The x-axis and y-axis taken together determine a plane known as ______.

**(ii)**The coordinates of points in the XY-plane are of the form _______.

**(iii)**Coordinate planes divide the space into ______ octants.

**Solution:**

**(i)** XY-plane

**(ii)** (x,
y, 0)

**(iii)** eight

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