Chapter 5

Understanding Elementary Shapes

Class 6 chapter 5 is Understanding Elementary Shapes. The chapter teaches students how to measure a line segment, about different types of polygons and their properties, triangles and their types. The new concept of angle and its measurement is introduced. A slight gist of solid or 3 D shapes towards the end of the chapter. MSVGo is a one-stop solution to enhance your knowledge and understanding of the subject at a very affordable price. All the topics of class 6th science are effortlessly explained on the MSVGo app. We provide notes, videos, numerous practice questions, and NCERT solutions for each chapter from class 6th to 12th. Download the MSVgo App for free and kickstart your journey of becoming a champ.

Topics covered in this chapter

Measuring Line Segments

Angles and its Types

Triangles and their Types

Polygons

Quadrilaterals

Solid Shapes or 3D Shapes

Perpendicular Lines
 

Measuring Line Segments

A line segment is a defined portion of a line. Line segments are measured by comparing their lengths. There are several ways to compare the length of line segments, such as:

 

(i) Comparison by observation: This is an eyeballing method; by just looking at the length of 2 line segments, we compare them. This method could prove inaccurate if there is a very small difference in the lengths. 

 (ii) Comparison by Tracing: The idea behind tracing is to put one line segment over the other to compare the lengths. A tracing paper is used to trace one line, and then it is put over the other to check which one is longer or shorter. Although it is comparatively an accurate method, it's very cumbersome.  

(iii) Comparison using Ruler and a Divider: Ruler (scale) and divider are measuring geometrical instruments. 


Ruler: a standard size ruler used by students is divided into 15 equal parts by marking. Each part is equal to 1cm, which is further divided into 10 parts of 1mm each. For e.g., to measure a line segment AB of 6.7cm on a ruler, we will measure 7 cm and 7mm. The ruler is marked from 0 cm to 15 cm. Position error can occur while measuring if the ruler is not placed.

Divider: A divider has 2 open ends that can stretch up to 180 degrees apart. To use the divider, open the divider and place its one end at point A of the line segment AB and the other end on point B.  Now, without disturbing the opening of the divider, place it over the ruler. The distance of one end of the divider from the other is equal to the length of the line segment AB.

An angle is made by two rays/lines that have either the same endpoint or starting point.

To understand angles, look at the wall clock hands in your home. The hour hand and the second hand are fixed at the centre. Both these hands act as a line segment or ray, and the arc between them forms the angle.

How to measure an angle: angles can be measured using a protector. A protector is a geometrical instrument in the shape of a ‘D’, with markings from zero to 180 degrees. The centre of the protector is placed exactly on top of the common point, making the angle. From the bottom i.e starting from zero degrees, the degree of the second line segment is measured, which is actually the desired angle.

Types of angle

Angles 

Degree 

Definition 

Complete angle 

360 degree

Suppose the clock starts at 12 and after completing One revolution it is again at 12. The angle made by a complete revolution is called a complete angle. 

Straight angle 

180 degree 

When the hour hand and the second hand are opposite each other, i.e., one at 12 and the other at 6, then it's called a straight angle. 

Right angle 

90 degree 

A quarter of a complete angle or half of the straight angle is a right angle. Formed when one hand of the clock is at 12 or 6 and other at 3 or 9. 

Obtuse angle 

180degree>obtuse angle>90 degree

An obtuse angle is formed when clock hands are positioned more than 3 hours apart, i.e., more than the quarter of a circle(clock). 

Acute angle 

<90degree

An acute angle is formed when clock hands are positioned less than 3 hours apart, i.e., less than the quarter of a circle. 

Reflex angle 

>180 degree 

Any angle greater than 180 degrees is called a reflex angle. 

 

Triangle is a polygon having three sides and three interior angles, formed by two 

adjacent sides with each other.

   

Types of triangle 

Based on the sides of a triangle

Scalene triangle 

Formed when all three sides are unequal.

Isosceles triangle

Formed when any 2 sides are equal.

Equilateral triangle 

Formed when all three sides are equal.

 

Based on angles of a triangle 

Acute-angled triangle

When all three angles are acute angles.

Obtuse-angled triangle

When any one angle is an obtuse angle 

Right-angled triangle

When any one angle is a right angle(90degrees)

 

Polygons are closed geometric shapes with at least 3 sides and 3 interior angles. The smallest polygon is a triangle. Based on the number of sides, polygons are of different types.

Polygons 

Sides 

Triangle 

A polygon with 3 sides and 3 angles 

Quadrilateral 

A polygon with 4 sides and 4 angles 

Pentagon 

A polygon with 5 sides and 5 angles 

Hexagon 

A polygon with 6 sides and 6 angles 

Heptagon 

A polygon with 7 sides and 7 angles 

Octagon 

A polygon with 8 sides and 8 angles

Nonagon 

A polygon with 9 sides and 9 angles

Decagon 

A polygon with 10 sides and 10 angles

 

A Quadrilateral is a  polygon with 4 sides and 4 angles. Based on the lengths and angles of the quadrilateral, it is further classified into different shapes.

Shapes 

Properties 

Square 

A quadrilateral with four equal sides and 4 right angles. 

Rectangle 

A quadrilateral with equal opposite sides and all right angles. 

Rhombus 

A quadrilateral with 4 equal sides.

Parallelogram 

A quadrilateral with opposite parallel sides.

Trapezium 

A quadrilateral with one pair of parallel sides. 

 

A 3-dimensional shape(3D shape) or a solid shape is defined as shapes that have 3 dimensions: length, breadth and height. 

For example: cube, cylinder, cuboid, sphere, etc

Some Properties of 3D shapes.

Faces: sides of 3D shapes are called faces.

Edge: the ends of line segments joining the two faces are called edges or corners.

Vertex: the common point where three edges meet is called a vertex. 

 

Special 3D shapes

Prism: Prism is a three-dimensional solid, with one of its faces as a triangle. 

  • Triangular prism: The triangular face is the base of the prism; therefore, it's called a triangular prism. Triangular prisms are used in laboratories. 

  • Rectangular prism: prism with two identical bases and other faces being rectangles. 

Pyramid: It's a 3D solid with a single base and other triangular faces.

     1. How will these chapter-wise solutions help me score more in NCERT Solutions for Class 6 Maths?

It helps you understand the topics in a much better and clearer way. The solutions are designed and written well-structured to teach students how to write answers in the exam.

     2. Can I access these chapters for free?

Yes, you can access these chapters for free on the NCERT website or the MSVGo app.

     3. How can I practice essential questions for all chapters present in NCERT Solutions class 6maths?

You can get practice questions for each chapter on the MSVGo app. The MSGVo app has many practice questions related to every topic of all chapters. They also provide precise and easily understandable notes for each chapter on their app.

 

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