NCERT Solutions for Class 11 Maths Chapter 11 Introduction to Three Dimensional Geometry Ex 11.1
Ex 11.1 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 11.1 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 11.1 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 11.1 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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NCERT Solutions for Maths Class 9