Contents

- 1 NCERT Solutions for Class 6 Maths Chapter 4 Basic Geometrical Ideas
- 1.1 Chapter 4 Basic Geometrical Ideas Exercise 4.1
- 1.2 Chapter 4 Basic Geometrical Ideas Exercise 4.2
- 1.3 Chapter 4 Basic Geometrical Ideas Exercise 4.3
- 1.4 Chapter 4 Basic Geometrical Ideas Exercise 4.4
- 1.5 Chapter 4 Basic Geometrical Ideas Exercise 4.5
- 1.6 Chapter 4 Basic Geometrical Ideas Exercise 4.6

NCERT Solutions for Class 6 Maths Chapter 4 Basic Geometrical Ideas are part of NCERT Solutions for Class 6 Maths. Here we have given NCERT Solutions for Class 6 Maths Chapter 4 Basic Geometrical Ideas.

Board |
CBSE |

Textbook |
NCERT |

Class |
Class 6 |

Subject |
Maths |

Chapter |
Chapter 4 |

Chapter Name |
Basic Geometrical Ideas |

Exercise |
Ex 4.1, Ex 4.2, Ex 4.3, Ex 4.4, Ex 4.5, Ex 4.6 |

Number of Questions Solved |
23 |

Category |
NCERT Solutions |

## NCERT Solutions for Class 6 Maths Chapter 4 Basic Geometrical Ideas

### Chapter 4 Basic Geometrical Ideas Exercise 4.1

Question 1.

Use the figure to name:

**(a)** Five points

**(b)** A line

**(c)** Four rays

**(d)** Five line segments

Solution:

Clearly, from the given figure

**(a)** 5 points are points, O, C, B, D and E.

**(b)** A line is [altex]\overleftrightarrow { BD } [/latex]

**(c)** 4 rays are and .

**(d)** 5 line segments are and .

Question 2.

Name the line given in all possible (twelve) ways, choosing only two letters at a time from the four given.

Solution:

All the possible ways of naming the given by choosing only two letters at a time out of 4 letters are

and .

Question 3.

Use the figure to name :

**(a)** Line containing point E.

**(b)** Line passing through A.

**(c)** Line on which O lies.

**(d)** Two pairs of intersecting lines.

Solution:

Clearly, from the given figure

**(a)** Line containing pqint E is .

**(b)** Line passing through A is .

**(c)** O lies on the line .

**(d)** Two pairs of intersecting lines are and .

Question 4.

How many lines can pass through

**(a)** one given point?

**(b)** two given points?

Solution:

**(a)** An unlimited number of lines can be drawn passing through a given point.

**(b)** Exactly one line can be drawn passing through two different given points in a plane.

Question 5.

Draw a rough figure and label suitably in each of the following cases:

**(a)** Point P lies on .

**(b)** and intersect at M.

**(c)** Line l contains E and F but not D.

**(d)** and meet at O.

Solution:

A rough figure and labelled suitably for the given cases are as under:

**(a)** Point P lies on :

**(b)** and intersect at M:

**(c)** Line l contains E and F but not D:

**(d)** and meet at O.

Question 6.

Consider the following figure of line MN. Say whether following statements are true or false in context of the given figure.

**(a)** Q, M, O, N, P are points on the line .

**(b)** M, O, N are points on a line segment .

**(c)** M and N are end points of line segment .

**(d)** O and N are end points of line segment .

**(e)** M is one of the end points of line segment .

**(f)** M is point on ray .

**(g)** Ray is different from ray .

**(h)** Ray is same as ray .

**(i)** Ray is not opposite to ray .

**(j)** O is not an initial point of .

**(k)** N is the initial point of and .

Solution:

In the context of the given figure, the given statement is:

**(a)** True

**(b)** True

**(c)** True

**(d)** False

**(e)** False

**(f)** False

**(g)** True

**(h)** False

**(i)** True

**(j)** False

**(k)** True

### Chapter 4 Basic Geometrical Ideas Exercise 4.2

Question 1.

Classify the following curves as

**(i)** Open or

**(ii)** Closed.

Solution:

Open curves are (a) and (c) and closed curves are (b), (d) and (e).

Question 2.

Draw rough diagrams to illustrate the following:

**(a)** Open curve

**(b)** Closed curve

Solution:

Rough diagram to illustrate

**(a) Open curve is**

**(b) Closed curve is**

Question 3.

Draw any polygon and shade its interior.

Solution:

We know that in a closed curve, the interior is inside of the curve. Thus, shaded portion of the polygon indicate its interior.

Question 4.

Consider the given figure and answer the questions:

**(a)** Is it a curve?

**(b)** Is it closed?

Solution:

**(a)** Yes, the given figure represents a curve.

**(b)** Yes, the curve is closed.

Question 5.

Illustrate, if possible, each one of the following with a rough diagram:

**(a)** A closed curve that is not a polygon.

**(b)** An open curve made up entirely of line segments.

**(c)** A polygon with two sides.

Solution:

**(a)** Impossible, as a close plane figure bounded by lines is called a polygon.

**(b)** Yes, it may be as

**(c)** No, impossible, as a polygon of two sides cannot be drawn.

### Chapter 4 Basic Geometrical Ideas Exercise 4.3

Question 1.

Name the angles in the given figure.

Solution:

The angles in the given figure are named as ?ABC, ?BCD, ?CDA and ?DAB.

Question 2.

In the given diagram, name the point(s)

**(a)** In the interior of ∠DOE

**(b)** In the exterior of ∠EOF

**(c)** On ∠EOF

Solution:

Clearly, from the given figure :

**(a)** The point A lies in the interior of ∠DOE. .

**(b)** The points A and C lie in the exterior of ∠EOF.

**(c)** The points E, B, O and F lie on ∠EOF.

Question 3.

Draw rough diagrams of two angles such that they have

**(a)** One point in common

**(b)** Two points in common

**(c)** Three points in common

**(d)** Four points in common

**(e)** One ray in common

Solution:

**(a)** The diagram is shown as below

Here, ∠ROQ and ∠QOP have one point O in common.

**(b)** The diagram is shown as below

Here, ∠MON and ∠ONR have two points O and N in common.

**(c)** Drawing a diagram of two angles, such that they have three points in common, is not possible.

**(d)** Drawing a diagram of two angles, such that they have four points in common, is not possible.

**(e)** In the figure given below, ∠SOT and ∠POT have one ray in common.

### Chapter 4 Basic Geometrical Ideas Exercise 4.4

Question 1.

Draw a rough sketch of a triangle ABC. Mark a point P in its interior and a point Q in its exterior. Is the point A in its exterior or in its interior?

Solution:

Rough sketch of a ∠ABC as shown.

Points P and Q are marked in the interior and exterior of ∆ABC.

Point A lies on the ∆ABC.

Question 2.

**(a)** Identify three triangles in the figure.

**(b)** Write the names of seven angles.

**(c)** Write the names of six line segments.

**(d)** Which two triangles have ZB as common?

Solution:

**(a)** Three triangles are identified in the figure as ∆ ABC, ∆ ABD and ∆ ACD.

**(b)** The names of seven angles are ∠BAD, ∠BAC, ∠CAD, ∠ABD, ∠ACD, ∠ADC and ∠ADB.

**(c)** The names of six line segments are AB, BD, DC, CA, BC and AD.

**(d)** ∆ ABC and ∆ ABD have ∠B as common.

### Chapter 4 Basic Geometrical Ideas Exercise 4.5

Question 1.

Draw a rough sketch of a quadrilateral PQRS. Draw its diagonals. Name them. Is the meeting point of the diagonals in the interior or exterior of the quadrilateral?

Solution:

PQRS is a quadrilateral having PR and QS as its diagonals intersecting at the point O, which is in the interior of the quadrilateral PQRS.

Question 2.

Draw a rough sketch of a quadrilateral KLMN. State,

**(a)** two pairs of opposite sides,

**(b)** two pairs of opposite angles,

**(c)** two pairs of adjacent sides,

**(d)** two pairs of adjacent angles.

Solution:

KLMN is a quadrilateral.

**(a)** KL, MN and LM, KN are two pairs of its opposite sides.

**(b)** ∠K, ∠M and∠L, ∠N are two pairs of opposite angles.

**(c)** KL, LM and KN, NM are two pairs of adjacent sides.

**(d)** ∠K, ∠N and ∠L, ∠M are two pairs of adjacent angles.

Question 3.

Investigate:

Use strips and fasteners to make a triangle and a quadrilateral.

Try to push inward at any one vertex of the triangle. Do the same to the quadrilateral.

Is the triangle distorted? Is the quadrilateral distorted? Is the triangle rigid?

Why is it that structures like electric towers make use of triangular shapes and not quadrilaterals?

Solution:

On pushing inward at any one vertex of the triangle, we find that the triangle is not distorted. Whereas doing so with the quadrilateral we find that it is distorted. Triangle is rigid. Thus, we make use of triangular shapes in structures like electric towers as triangular shapes are more rigid.

### Chapter 4 Basic Geometrical Ideas Exercise 4.6

Question 1.

From the figure, identify:

**(a)** the centre of circle

**(b)** three radii

**(c)** a diameter

**(d)** a chord

**(e)** two points in the interior

**(f)** a point in the exterior

**(g)** a sector

**(h) **a segment

Solution:

**(a)** O is the centre of the circle.

**(b)** OA, OB and OC are three radii of circle.

**(c)** AC is a diameter of circle.

**(d)** ED is a chord of circle.

**(e)** Points O and P are in the interior of circle.

**(f)** Point Q is in the exterior of circle.

**(g)** OAB is a sector of circle.

**(h)** Shaded region in the interior of a circle enclosed by a chord ED.

Question 2.

**(a)** Is every diameter of a circle also a chord?

**(b)** Is every chord of a circle also a diameter?

Solution:

**(a)** Yes, a diameter is the longest chord.

**(b)** Not always.

Question 3.

Draw any circle and mark

**(a)** its centre

**(b)** a radius

**(c)** a diameter

**(d)** a Sector

**(e)** a segment

**(f)** a point in its interior

**(g)** a point in its exterior

**(h)** an arc

Solution:

Draw any circle and its various parts are as under :

**(a)** Its centre is O.

**(b)** Its radii are OA, OB and OC.

**(c)** Its diameter is AOC.

**(d)** Its sector is OAB.

**(e)** Shaded region in the interior of a circle enclosed by a chord PQ.

**(f)** M is a point in its interior.

**(g)** N is a point in its exterior.

**(h)** BC is an arc.

Question 4.

Say true or false:

**(a)** Two diameters of a circle will necessarily intersect.

**(b)** The centre of a circle is always in its interior.

Solution:

**(a)** True, because each diameter passes through the centre of a circle.

**(b)** True.

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