Understanding Diagonals in Geometry | 3rd Grade Maths Term 3 Chapter 1

Geometry | Term 3 Chapter 1 | 3rd Maths

Chapter: 3rd Maths : Term 3 Unit 1 : Geometry

Diagonal

Diagonal is the line joining opposite corners of a geometrical shape.

Observe the corners of the square.

The line joining opposite corners of a square is called the diagonal of the square.

A square has two diagonals.

Diagonals of a cube:

A Cube has six square faces. Each square has two diagonals.

Diagonals in the faces = 6 × 2 = 12.

Diagonals in the inner sides of 4 corners = 4.

Total number of diagonals of a cube = 12 + 4 = 16.

Activity & Questions

Draw the diagonals for the given rectangle.

How many diagonals will be there in a cuboid?

16.

Match the Following

Match the properties of 2D shapes by observing their sides and corners (vertices).

Properties

(1) Opposite sides are equal.

(2) There are no sides and corners.

(3) Sides may or may not be equal.

(4) All the four sides are equal.

Shapes

(a) Circle

(b) Triangle

(c) Square

(d) Rectangle

Click to see the Answers

1. Opposite sides are equal. - (d)

2. There are no sides and corners. - (a)

3. Sides may or may not be equal. - (b)

4. All the four sides are equal. - (c)