Finding Perimeter of Rectangle, Squares and Triangle

1. Perimeter
Rectangles, Squares,
and Triangles

2. Objectives:
a.To find the perimeter of any given
closed plane figure in different
situations.
b.To draw any given closed plane figure
in different situations.
c.To value any given closed plane figure
in different situations.

3. Review:
Ask what unit of measurement and
measuring tool is appropriate for the
following. (Ex. Centimeter =cm, meter=m)
1. Sides of a handkerchief
2. Length of a ball pen
3. Sides of a blackboard
4. Sides of your notebook

4. Show a plain handkerchief.
Ask:
What is the shape of this
handkerchief? Do you carry your
handkerchief everyday? Why? What
are the uses of a handkerchief?
How will you describe a handkerchief?

5. Perimeter
Rectangles, Squares,
and Triangles

6. What is Perimeter?
Perimeter is the distance around
a two dimensional shape, or the
measurement of the distance
around something; the length of
the boundary.

7. What is a rectangle?
A rectangle has:
4 sides
4 square corners
Opposite sides are of equal lengths
Opposite sides are directly across
from each other

8. To find the perimeter of a
rectangle:
6 cms Use the formula
P= 2 (length + width)
9 cms
If length of a rectangl is 9 cms and its width is 6 cms.
Find the perimeter of the rectangle.
Sol: P = 2(l+b)
= 2(9+6)
= 2(15)
= 30 cms

9. What is a square?
A square has:
4 equal sides
4 right angles

10. To find the perimeter of a square:
12 cms
Use the formula:
Find the perimeter of a square whose side is 12
cms.
Sol: P = 4 x side
= 4 x 12
= 48 cms

11. What is a triangle?
A triangle has 3 sides.
All triangles may not look the same,
but they all have 3 sides.

12. To find the perimeter of a
triangle:
6 cms 9 cms
P = a + b + c
Use the formula:
P = a + b + c
5 cms
Find the perimeter of a triangle whose sides are
6cms, 9cms and 5cms.
Sol: P = a + b + c
= 6 + 9 + 5
= 15 + 5
= 20 cms

13. Outdoor Learning:
Explore the OLEP area of the
school. Let the learners draw
and find at least one closed
plane figures and find the
perimeter of it.

14. Home activities.
Draw and find the
perimeter of your table
at home.