Exercise 11.1 (Revised) - Chapter 12 - Introduction To Three Dimensional Geometry - Ncert Solutions class 11 - Maths
Updated On 26-08-2025 By Lithanya
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NCERT Solutions Class 11 Maths Chapter 11: Introduction To Three Dimensional Geometry
Ex 11.1 Question 1.
A point is on the $x$-axis. What are its $y$-coordinates and $z$-coordinates?
Answer.
We know that coordinates of any point on the $x$-axis will be $(x, 0,0)$. Therefore, $y$ - coordinate and $z$-coordinate of the point are zero.
Ex 11.1 Question 2.
A point is on $X Z-$ plane. What can you say about its $y$-coordinate?
Answer.
We know that coordinates of any point in XZ-plane will be $(x, 0, z)$. Therefore $y-$ coordinate of the point is zero.
Ex 11.1 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)
$
Answer.
Point $(1,2,3)$ lies in I octant
Point $(4,-2,3)$ lies in IV octant
Point $(4,-2,-5)$ lies in VIII octant
Point $(4,2,-5)$ lies in V octant
Point(-4,2,-5) lies in VI octant
Point $(-4,2,5)$ lies in II octant
Point $(-3,-1,6)$ lies in III octant,
Point (2,-4,-7) lies in VII octant
Ex 11.1 Question 4.
Fill in the blanks:
(i) The $x$-axis and $y$-axis taken together determine a plane known as $\qquad$ .
(ii) The coordinates of points in the XY-plane are of the form $\qquad$ .
(iii) Coordinates planes divide the space into $\qquad$ octants.
Answer.
(i) XY-plane
(ii) $(x, y, 0)$
(iii) Eight
