These Introduction To Three Dimensional Geometry Class 11 NCERT Questions and Answers are most important for your upcoming examinations including JEE Main & JEE Advanced. These Introduction To Three Dimensional Geometry Class 11 NCERT Questions and Answers will help you to score good marks in your exams by helping you to prepare the concepts better and hence, help you to understand the concepts more clearly.

## Introduction To Three Dimensional Geometry Class 11 NCERT Questions

1. Equation of Y-axis is considered as

(A) x = 0, y = 0

(B) y = 0, z = 0

(C) z = 0, x = 0

(D) none of these

**Answer:** z = 0, x = 0

2. x-axis is the intersection of two planes

(A) xy and xz

(B) yz and zx

(C) xy and yz

(D) none of these

**Answer:** xy and xz

3. If the distance between the points (a,0,1) and (0,1,2) is ?27, then the value of a is

(A) 5

(B) ± 5

(C) -5

(D) none of these

**Answer:** ± 5

4. Distance of the point (3,4, 5) from the origin (0, 0, 0) is

(A) ?50

(B) 3

(C) 4

(D) 5

**Answer:** ?50

5. What is the length of foot of perpendicular drawn from the point P(3,4, 5) on y-axis?

(A) ?41

(B) ?34

(C) 5

(D) None of these

**Answer:** ?34

6. The distance of point P(3,4, 5) from the yz-plane is

(A) 3 units

(B) 4 units

(C) 5 units

(D) 550

**Answer:** 3 units

7. L is the foot of the perpendicular drawn from a point (3, 4, 5) on xaxis. The coordinates of L are

(A) (3,0,0)

(B) (0,4,0)

(C) (0, 0, 5)

(D) none of these

**Answer:** (3,0,0)

8. L is the foot of the perpendicular drawn from a point P(3, 4, 5) on the xy-plane. The coordinates of point L are

(A) (3,0,0)

(B) (0,4,5)

(C) (3, 0, 5)

(D) none of these

**Answer:** none of these

9. The locus of a point for which x = 0 is

(A) xy-plane

(B) yz-plane

(C) zx-plane

(D) none of these

**Answer:** yz-plane

10. The locus of a point for which y = 0, z = 0 is

(A) equation of x-axis

(B) equation of y-axis

(C) equation at z-axis

(D) none of these

**Answer:** equation of x-axis

11. A plane is parallel to yz-plane so it is perpendicular to

(A) x-axis

(B) y-axis

(C) z-axis

(D) none of these

**Answer:** x-axis

12. The point (-2, -3, -4) lies in the

(A) First octant

(B) Seventh octant

(C) Second octant

(D) Eighth octant

**Answer:** Seventh octant

13. Equation of Y-axis is considered as

(A) x = 0, y = 0

(B) y = 0, z = 0

(C) z = 0, x = 0

(D) none of these

**Answer:** z = 0, x = 0

14. In a three dimensional space, the equation 3x – 4y = 0 represents

(A) a plane containing Y axis

(B) none of these

(C) a plane containing Z axis

(D) a plane containing X axis

**Answer:** a plane containing Z axis

15. Three planes x + y = 0, y + z = 0, and x + z = 0

(A) none of these

(B) meet in a line

(C) meet in a unique point

(D) meet taken two at a time in parallel lines

**Answer:** meet in a unique point

16. The points on the y- axis which are at a distance of 3 units from the point (2, 3, -1) is

(A) either (0, -1, 0) or (0, -7, 0)

(B) either (0, 1, 0) or (0, 7, 0)

(C) either (0, 1, 0) or (0, -7, 0)

(D) either (0, -1, 0) or (0, 7, 0)

**Answer:** either (0, -1, 0) or (0, 7, 0)

17. The cartesian equation of the line is 3x + 1 = 6y – 2 = 1 – z then its direction ratio are

(A) 1/3, 1/6, 1

(B) -1/3, 1/6, 1

(C) 1/3, -1/6, 1

(D) 1/3, 1/6, -1

**Answer:** 1/3, 1/6, 1

18. The equation of the set of point P, the sum of whose distance from A(4, 0, 0) and B(-4, 0, 0) is equal to 10 is

(A) 9x² + 25y² + 25z² + 225 = 0

(B) 9x² + 25y² + 25z² – 225 = 0

(C) 9x² + 25y² – 25z² – 225 = 0

(D) 9x² – 25y² – 25z² – 225 = 0

**Answer:** 9x² + 25y² + 25z² – 225 = 0

19. A vector r is equally inclined with the coordinate axes. If the tip of r is in the positive octant and |r| = 6, then r is

(A) 2?3(i – j + k)

(B) 2?3(-i + j + k)

(C) 2?3(i + j – k)

(D) 2?3(i + j + k)

**Answer:** 2?3(i + j + k)

20. The maximum distance between points (3sin ?, 0, 0) and (4cos ?, 0, 0) is

(A) 3

(B) 2

(C) 4

(D) 5

**Answer:** 5