This document provides a lesson on polygons and calculating perimeter of squares. It begins with an introduction to polygons, defining them as closed, flat shapes made of straight lines with three or more sides. It then focuses on quadrilaterals, specifically defining squares as quadrilaterals with four equal sides forming right angles. The document provides formulas for calculating the perimeter of a square when given the length of a side or vice versa. It includes examples of calculating perimeter when given side length or when given total perimeter. It emphasizes perimeter as the total distance around a closed shape and provides real-life examples of measuring perimeter.

1. Week 7
Virtual Teaching
Phase-II
Lesson code: 5M25

2. We will start our daily class by reciting dua for knowledge
RECITE IT WITH YOUR TEACHER

3. Contents
Introduction to
polygons
Introduction to
Quadrilateral
Finding perimeter
of a square
Finding length of
a side of square

4. Geometry is a branch of mathematics that deals with
shapes and figures.
Geometry explains how to build or draw shapes, measure
them, and compare them.
Geometry:
✓ Minimum 3 line segments make a
closed shape that is called Triangle.
A part of line with two end points.
Line Segment:

5. Polygon:
Poly means “many”
Gon means “angles”
Polygon are the closed flat
figures , made up of straight
lines, that have many
angles(vertices) in them.
Polygon are the closed shapes
having three(3) or more
sides(line segments).
OR
Triangle
3-sided polygon
Quadrilateral
4-sided polygon
Pentagon
5-sided polygon

6. 2D (2-Dimensional) Shapes
2D stands for 2-dimensional. 2-dimensional shapes are flat
and only have two dimensions: length and width.
They include squares, rectangles, circles, triangles, and
more.
IMPORTANT
A circle is also a plane figure but it is not considered a
polygon, because it is a curved shape and does not have
sides. Therefore, we can say,
ALL THE POLYGONS ARE 2D SHAPES BUT
NOT ALL THE TWO-DIMENSIONAL FIGURES ARE POLYGONS.

7. LIST OF POLYGON NAMES
DEPENDING ON THE NUMBER OF SIDES

8. Quadrilateral
A Quadrilateral is a polygon having a number of sides equal to four.

9. Quadrilateral
A Quadrilateral is a polygon having a number of sides equal to four.
SQUARE:
Square is a quadrilateral having four equal sides
and 4 right angles.
90° 90°
90° 90°
E
F G
H
Properties of Square:
• All sides are equal in measurement.
• All angles are of 90-degrees measurement.

10. Perimeter is the total length of
the boundary of any closed region.
Perimeter:
4 × length of a side of square
OR
length + length + length + length
Perimeter of a square:
Important notes about finding perimeter
The units to measure the perimeter are
m (meters) , cm (centimeters) etc

11. REAL LIFE SITUATIONS
DESCRIBING PERIMETER
The length of the fence around a
closed region
The total length of a photo frame
The length of hedge around a garden
The total length of constructing
boundary wall around a building

12. Derivation of formula of length of a side of square
which is used when perimeter of square is given.
As, Perimeter of a square = 4 × length of a side of square
𝑫𝒊𝒗𝒊𝒅𝒊𝒏𝒈 𝒃𝒐𝒕𝒉 𝒔𝒊𝒅𝒆𝒔 𝒃𝒚 𝟒
=
OR
4 × l = Perimeter of a square
Length of a side of square =
Perimeter of square
𝟒
OR
=

13. IMPORTANT

14. Perimeter of a square = 4 × length of a side of square
s
𝑻𝒐 𝒇𝒊𝒏𝒅 𝒑𝒆𝒓𝒊𝒎𝒆𝒕𝒆𝒓 𝒐𝒇 𝒔𝒒𝒖𝒂𝒓𝒆 𝒘𝒉𝒆𝒏 𝒊𝒕𝒔 𝒐𝒏𝒆 𝒔𝒊𝒅𝒆 𝒍𝒆𝒏𝒈𝒕𝒉 𝒊𝒔 𝒈𝒊𝒗𝒆𝒏
=
𝑻𝒐 𝒇𝒊𝒏𝒅 𝒔𝒊𝒅𝒆 𝒍𝒆𝒏𝒈𝒕𝒉 𝒐𝒇 𝒂 𝒔𝒒𝒖𝒂𝒓𝒆 𝒘𝒉𝒆𝒏 𝒊𝒕𝒔 𝒑𝒆𝒓𝒊𝒎𝒆𝒕𝒆𝒓 𝒊𝒔 𝒈𝒊𝒗𝒆𝒏

15. Do all classwork
questions on
rough notebook

16. Total length of the boundary = 38 cm
Perimeter = Total length of the boundary
Question#1:
Find the perimeter of a square shaped photo frame when the
total length of its boundary is 38cm.
Perimeter of square shaped photo frame is 38 cm
Perimeter of square shaped photo frame = 𝟑𝟖 𝒄𝒎
Solution:

17. Total length of the boundary wall = perimeter = ?
Length of one side = 27 m
Question#2:
Find the total length of a boundary wall around a square shaped
building when length of its one side is 27 m.
Total length of the square shaped boundary wall is 108 m
Perimeter of square = 4 × length of a side
= 4 × 27 m
=
Solution:

18. =
Solution:
Length of a side of the square = ?
Perimeter of the square = 56 cm
Question#3:
Find length of a side of a square whose perimeter is 56cm.
Length of a side of the square is 14 cm
=
1
14
length = 𝟏𝟒 𝒄𝒎

19. Recheck all solutions of classwork questions by yourself
through shared PDF
ALSO REVISE TODAY’S COMPLETE LECTURE
Do Live worksheet