Maths NCERT Exemplar Solutions Class 11th Chapter Twelve: Overview, Questions, Preparation

Maths NCERT Exemplar Solutions Class 11th Chapter Twelve 2025 ( Maths NCERT Exemplar Solutions Class 11th Chapter Twelve )

Raj Pandey
Updated on Aug 6, 2025 10:57 IST

By Raj Pandey

Table of content
  • Introduction to Three Dimensional Geometry Short Answer Type Questions
  • Introduction to Three Dimensional Geometry Long Answer Type Questions
  • Introduction to Three Dimensional Geometry Objective Type Questions
  • Introduction to Three Dimensional Geometry Fill in the blank Type Questions
  • Introduction to Three Dimensional Geometry Matching Type Questions
  • JEE Mains 2021
Maths NCERT Exemplar Solutions Class 11th Chapter Twelve Logo

Introduction to Three Dimensional Geometry Short Answer Type Questions

Locate the following points:

i. (1, –1, 3),

ii. (–1, 2, 4)

iii. (–2, –4, –7),

iv. (–4, 2, –5).

Sol.

( i ) L o c a t i o n o f P ( 1 , 1 , 3 ) = ( x , y , z ) = I Voctant ( i i ) L o c a t i o n o f Q ( 1 , 2 , 4 ) = ( x , y , z ) = I Ioctant ( i i i ) L o c a t i o n o f R ( 2 , 4 , 7 ) = ( x , y , z ) = V I Ioctant ( i v ) L o c a t i o n o f S ( 4 , 2 , 5 ) = ( x , y , z ) = V I  octant

Name the octant in which each of the following points lies:

i. (1, 2, 3),

ii. (4, –2, 3),

iii. (4, –2, –5),

iv. (4, 2, –5),

v. (–4, 2, 5),

vi. (–3, –1, 6),

vii. (2, –4, –7),

viii. (–4, 2, –5).

Sol:

( i )Point ( 1 , 2 , 3 ) l i e s i n IOctant ( i i )Point ( 4 , 2 , 3 ) l i e s i n I VOctant ( i i i )Point ( 4 , 2 , 5 ) l i e s i n V I I I  Octant ( i v )Point ( 4 , 2 , 5 ) l i e s i n VOctant ( v )Point ( 4 , 2 , 5 ) l i e s i n I IOctant ( v i )Point ( 3 , 1 , 6 ) l i e s i n I I IOctant ( v i i )Point ( 2 , 4 , 7 ) l i e s i n V I I IOctant ( v i i i )Point ( 4 , 2 , 5 ) l i e s i n V IOctant

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Commonly asked questions
Q:  

Show that if x 2 + y 2 = 1 , then the point   ( x , y , 1 x 2 y 2 ) is at a distance of 1 unit from the origin.

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Q:  

Name the octant in which each of the following points lies:

i. (1, 2, 3),

ii. (4, –2, 3),

iii. (4, –2, –5),

iv. (4, 2, –5),

v. (–4, 2, 5),

vi. (–3, –1, 6),

vii. (2, –4, –7),

viii. (–4, 2, –5).

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Q:  

Let   A , B , C be the feet of perpendiculars from a point   P on the x -, y -, and z -axes, respectively. Find the coordinates of   A , B , C in each of the following where the point   P is:

i. A = (3, 4, 2),

ii. (–5, 3, 7),

iii. (4, –3, –5).

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Try these practice questions

Q1:

Let f : R →R be a continuous function such that f(3x) – f(x) =. If f(8) = 7, then f(14) is equal to:

Q2:

Let O be the origin and A be the point z1 = 1 + 2i. If B is the point z2, Re(z2) < 0, such that OAB is a right angled isosceles triangle with OB as hypotenuses, then which of the following is NOT true?

View Full Question

Q3:

If the system of linear equations

8x + y + 4z = -=-2

x + y + z = 0

λ x - 3y = μ  

has infinitely many solutions, then the distance of the point  ( λ , μ 1 2 )  from the plane 8x + y + 4z + 2 = 0 is:

View Full Question

Maths NCERT Exemplar Solutions Class 11th Chapter Twelve Logo

Introduction to Three Dimensional Geometry Long Answer Type Questions

1. Show that the three points A ( 2 , 3 , 4 )  ,  B ( 1 , 2 , 3 )  , and  C ( 4 , 1 , 1 0 )  are collinear and find the ratio in which  C  divides  A B  .

Sol:

G i v e n  points a r e A ( 2 , 3 , 4 ) , B ( 1 , 2 , 3 ) a n d C ( 4 , 1 , 1 0 ) A B = ( 2 + 1 ) 2 + ( 3 2 ) 2 + ( 4 + 3 ) 2 = 9 + 1 + 4 9 = 5 9 B C = ( 1 + 4 ) 2 + ( 2 1 ) 2 + ( 3 + 1 0 ) 2 = 9 + 1 + 4 9 = 5 9 A C = ( 2 + 4 ) 2 + ( 3 1 ) 2 + ( 4 + 1 0 ) 2 = 3 6 + 4 + 1 9 6 = 2 3 6 = 2 5 9 A B + B C = A C 5 9 + 5 9 = 2 5 9 H e n c e , A , B a n d C a r e c o l l i n e a r a n d A C : B C = 2 5 9 : 5 9 = 2 : 1 H e n c e , C d i v i d e s A B i s 2 : 1 e x t e r n a l l y .

2. Prove that the points ( 0 , 1 , 7 )  ,  ( 2 , 1 , 9 )  , and  ( 6 , 5 , 1 3 )  are collinear. Find the ratio in which the first point divides the join of the other two.
L e t t h e g i v e n  points a r e A ( 0 , 1 , 7 ) , B ( 2 , 1 , 9 ) , C ( 6 , 5 , 1 3 ) A B = ( 2 0 ) 2 + ( 1 + 1 ) 2 + ( 9 + 7 ) 2 = 4 + 4 + 4 = 1 2 = 2 3 B C = ( 6 2 ) 2 + ( 5 1 ) 2 + ( 1 3 + 9 ) 2 = 1 6 + 1 6 + 1 6 = 4 8 = 4 3 A C = ( 6 0 ) 2 + ( 5 + 1 ) 2 + ( 1 3 + 7 ) 2 = 3 6 + 3 6 + 3 6 = 1 0 8 = 6 3 2 3 + 4 3 = 6 3 i . e . , A B + B C = A C A B : A C = 2 3 : 6 3 = 1 : 3 H e n c e ,  point A d i v i d e s B a n d C i n 1 : 3 e x t e r n a l l y .
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Commonly asked questions
Q:  

Show that the three points A(2,3,4) , B(1,2,3) , and C(4,1,10) are collinear and find the ratio in which C divides AB .

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Q:  

Prove that the points (0,1,7) , (2,1,9) , and (6,5,13) are collinear. Find the ratio in which the first point divides the join of the other two.

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Q:  

What are the coordinates of the vertices of a cube whose edge is 2 units, one of whose vertices coincides with the origin and the three edges passing through the origin, coincides with the positive direction of the axes through the origin?

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Maths NCERT Exemplar Solutions Class 11th Chapter Twelve Logo

Introduction to Three Dimensional Geometry Objective Type Questions

1. The distance of point P ( 3 , 4 , 5 )  from the y z -plane is

(a) 3 units

(b) 4 units

(c) 5 units

(d) 550

Sol.

G i v e n  point i s P ( 3 , 4 , 5 )  Distance o f P f r o m y z p l a n e = ( 0 3 ) 2 + ( 4 4 ) 2 + ( 5 5 ) 2 = 9 = 3 u n i t s H e n c e , t h e c o r r e c t o p t i o n i s ( a ) .

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

(a) 4 1  

(b) 3 4  

(c) 5

(d) None of these

Sol. O n y - a x i s , x = 0 a n d z = 0 g i v e n point i s P ( 3 , 4 , 5 ) T h e point A i s ( 0 , 4 , 0 ) P A = ( 0 3 ) 2 + ( 4 4 ) 2 + ( 0 5 ) 2 = 9 + 0 + 2 5 = 3 4 H e n c e , t h e c o r r e c t o p t i o n i s ( b ) .
Q&A Icon
Commonly asked questions
Q:  

The distance of point P ( 3 , 4 , 5 )  from the y z -plane is

(a) 3 units

(b) 4 units

(c) 5 units

(d) 550

Q:  

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

(a) 4 1  

(b) 3 4  

(c) 5

(d) None of these

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Q:  

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

(a) 5 0    

(b)   3

(c)   4

(d)    5

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Maths NCERT Exemplar Solutions Class 11th Chapter Twelve Logo

Introduction to Three Dimensional Geometry Fill in the blank Type Questions

1. The three axes O X , O Y , O Z  determine ____.

Sol:

T h e t h r e e a x e s O X , O Y a n d O Z  determine t h r e e c o o r d i n a t e p l a n e s . H e n c e , t h e f i l l e r v a l u e i s t h r e e c o o r d i n a t e p l a n e s .

2. The three planes determine a rectangular parallelepiped which has ____ rectangular faces.

Sol:

T h r e e p a i r s . H e n c e , t h e v a l u e o f t h e f i l l e r i s t h r e e p a i r s .

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Commonly asked questions
Q:  

The three axes OX,OY,OZ determine ____.

Q:  

A line is parallel to xy -plane if all the points on the line have equal ____.

Q:  

If the midpoints of the sides of a triangle AB,BC,CA are D(1,2,3),E(3,0,1),F(1,1,4) , then the centroid of the triangle ABC is ____.

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Maths NCERT Exemplar Solutions Class 11th Chapter Twelve Logo

Introduction to Three Dimensional Geometry Matching Type Questions

Match each item given under Column C1 to its correct answer given under Column C2:

 Sol.  ( a ) I n x y - p l a n e , z - c o o r d i n a t e i s z e r o . H e n c e , ( a ) ( i i i ) . ( b ) T h e point ( 2 , 3 , 4 ) l i e s i n f i r s t octant . H e n c e , ( b ) ( i ) . ( c ) L o c u s o f t h e points w i t h x - c o o r d i n a t e i s z e r o i s y z - p l a n e . H e n c e , ( c ) ( i i ) . ( d ) A l i n e i s p a r a l l e l t o x - a x i s i f a n d o n l y i f a l l t h e points o n t h e l i n e h a v e e q u a l y a n d z - c o o r d i n a t e s . H e n c e , ( d ) ( v i ) . ( e ) x = 0 , y = 0 r e p r e s e n t s z - a x i s . H e n c e , ( e ) ( i v ) . ( f ) z = c r e p r e s e n t a p l a n e p a r a l l e l t o x y - p l a n e . H e n c e , ( f ) ( v ) . ( g ) T h e p l a n e s x = a , y = b r e p r e s e n t t h e l i n e p a r a l l e l t o z - a x i s . H e n c e , ( g ) ( v i i i ) . ( h ) C o o r d i n a t e s o f a point a r e t h e distances f r o m t h e o r i g i n t o t h e f e e t o f p e r p e n d i c u l a r f r o m t h e point o n t h e r e s p e c t i v e a x e s , H e n c e , ( h ) ( v i i ) . ( i ) A b a l l i s s o l i d r e g i o n i n t h e s p a c e e n c l o s e d b y a s p h e r e . H e n c e , ( i ) ( x ) . ( j ) T h e r e g i o n i n t h e p l a n e e n c l o s e d b y a c i r c l e i s k n o w n a s a d i s c . H e n c e , ( i ) ( i x ) .

 

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Commonly asked questions
Q:  

Match each item given under Column C1 to its correct answer given under Column C2:

Maths NCERT Exemplar Solutions Class 11th Chapter Twelve Logo

JEE Mains 2021

JEE Mains 2021

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Maths NCERT Exemplar Solutions Class 11th Chapter Twelve Exam

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