1

1. Of Some Plane Figures
Areas

2. Guess the
Shape
Guess the name of the
shape to be shown.

3. TRIANGLE
Guess the
Shape

4. SQUARE
Guess the
Shape

5. TRAPEZOID
Guess the
Shape

6. What is an
Area?

7. The amount of surface in a region is
it area. The area of any two-
dimensional figure can be
determined by imagining its surface
filled with square regions called
square units.
Area
Area

8. A square whose side is one unit
long has an area of one square unit.
The square centimeter is a standard
unit of area.
Square
Units
1
unit
1
unit

9. A rectangular region
whose length
measures 6 units and
whose width
measures 4 units.
How many square
units are there in its
surface?
4 units
6 units

10. There are 24 units. 24
is the product of 6
and 4. Thus, the
rectangular region
has 24 square units
in its surface
4 units
6 units

11. The area A of a square
of sides s is given by
𝐴 = 𝑠2
Area of
a Square
s
s

12. The area A of a square
of sides s is given by
𝐴 = 𝑠2
Area of a
Triangle
h
b
The area A of a
triangle with base b
and height h is given
by
𝐴 =
1
2
𝑏ℎ

13. The area A of a
parallelogram with
base b and height h
is given by
𝐴 = 𝑏ℎ
b
h
Area of a
Parallelogram

14. The area A of a
trapezoid with base
𝑏1 and 𝑏2 and height
h is given by
𝐴 =
1
2
ℎ(𝑏1 + 𝑏2)
𝑏1
h
𝑏2
Area of a
Trapezoid

15. The area A of a circle
of radius r is given
by
𝐴 = 𝜋𝑟2
Area of a
Circle
.
r

16. The area A of a circle
of radius r is given
by
𝐴 = 𝜋𝑟2
Area of a
Circle
.
r

17. Test
Yourself

18. Problem 1
Find the area of the
surface of circular
table whose
diameter is 60 cm.

19. Solution to Problem 1
Using the given formula
𝐴 = 𝜋𝑟2
d= 60 cm
r=
60𝑐𝑚
2
= 30 cm
𝐴 = 𝜋(30 𝑐𝑚)2
𝐴 = 2827.43 𝑐𝑚2

20. Solution to Problem 1
The area of the
circular table is
2827.43 𝑐𝑚2.

21. Problem 2
What is the floor
area of a square
room which
measures 5.5 m on
each of its sides?

22. Using the formula
for the area of
square, we have
𝐴 = 𝑠2
= (5.5 𝑚)2
= 30.25 𝑚2
Solution to Problem 2

23. Solution to Problem 2
Therefore, the floor
area of the room is
30.25 𝑚2
.

24. The area A of a circle
of radius r is give by
𝐴 = 𝜋𝑟2
.
Thank
you!