SDO TABACO CITY

Mathematics 4
Quarter 4 – Week 1
LAS 1.1 – Finding the Area of Irregular Figures Made up of Squares
and Rectangles Using sq. m and sq. m (M4ME-Iva-55)

LAS 1.2 – Finding the Area of Triangles, Parallelograms and

Trapezoids Using sq. cm and sq. m (M4ME-IVb-58)

Development Team

Writer
Sheina V. Bueno, Teacher II, Bogñabong ES

Editors/Reviewers
Emelda D. Bien, Teacher II, San Lorenzo ES
Jayson B. Baria, Teacher 1, Magapo ES
Efren B. Bonsa, PSDS, District 6
Dioleta B. Borais, EPS 1, Mathematics
 Republic of the Philippines
Department of Education
Region V-Bicol
SCHOOLS DIVISION OF TABACO CITY

Name: _____________________________ Sec: __________ Date: _________

Learning Area-Grade: Mathematics 4_______ Teacher: _____________________

LEARNING ACTIVITY SHEETS NO. 1.1

Finding the Area of Irregular Figures
Objective
Finds the area of irregular figures made up of squares and rectangles using
sq. cm and sq. m.

Learning Activity
An irregular figure is a figure that is not a standard geometric shape. Its area
cannot be calculated using any of the standard area formulas. But some irregular
figures are made up of two or more standard geometric shapes, the squares and
rectangles.

The area of a figure is the number of square units that fit inside it. To find the
area of an irregular shape that is made up of squares and rectangles:
1. Divide or cut the figure into squares and rectangles.
2. Find the area of each square or rectangles made.
3. Add the areas of the squares and/ or rectangles made to find the area of the
irregular figure; and
4. Express the area in sq. cm (cm2) or sq. m (m2). Triangles and quadrilaterals
are related according to sides and angles.

Example:
Find the area of the figure below.

Solution A: (Divide or cut the figure vertically)

There are two rectangles formed labeled A and B. To find

the area of the figure, you do these:

Area of Rectangle A: = l x w = 3 cm x 1 cm = 3 sq. cm

Area of Rectangle B: = l x w = 2 cm x 4 cm = 8 sq. cm
 Add the areas: 3 sq. cm + 8 sq. cm = 11 sq. cm

Solution B: (Divide or cut the figure horizontally)

There are two rectangles formed labeled A and B. to find

the area of the figure, you do these:

Area of Rectangle A: = l x w = 5 cm x 1 cm = 5 sq. cm

Area of Rectangle B: = l x w = 2 cm x 3 cm = 6 sq. cm
Add the areas: 5 sq. cm + 6 sq. cm = 11 sq. cm

Practice Exercises
A. Find the area of the following irregular figures.
1.
Area 1 = _______ x ______ = _________

Area 2 = _______ x ______ = _________

Total Area = _____________

2. Area 1 = _______ x ______ = _________

Area 2 = _______ x ______ = _________

Total Area = _____________

3. Area 1 = _______ x ______ = _________

Area 2 = _______ x ______ = _________

Area 3 = _______ x ______ = _________

Total Area = _____________

B. Solve for the area of the following irregular figures. Match it with their
answers in Column B.
Column A Column B
1. A. 67 m2

2. B. 84 m2

3. C. 30 cm2
 C. Find the area of the irregular figures.

1. 2. 3.

Evaluation
Find the area of the irregular figures below.
1. 2.

3. 4.

5.

Answer Key

Practice Exercises
A. 1. 39 m2 2. 52 cm2 3. 68 cm2
B. 1. C 2. A 3. B
C. 1. 117 cm2 2. 96 m2 3. 39 m2

References nurses.lumenlearning.com
Mathematics 4, Learner’s Material pages 196- 198
Mathematics 4, Teacher’s Guide pages 260- 264
Name: _____________________________ Sec: __________ Date: _________
Learning Area-Grade: Mathematics 4_______ Teacher: _____________________

LEARNING ACTIVITY SHEET NO. 1.2

Finding the Area of Triangles, Parallelograms and Trapezoids

Objective
Finds the area of triangles, parallelograms and trapezoids using sq. cm and
sq. m.

Learning Activity
The area (A) is the space enclosed by a plane figure. It is measured in square
units of length such as square centimeter (cm2) and square meter (m2).
To find the area of a parallelogram, multiply its base (b) and height (h).

A=bxh

To find the area of a triangle, get the half of the product of its base and height.

1
A = 2 (b x h)

To find the area of a trapezoid with bases (b1 and b2) and height (h), use the
formula:

(𝑏1 +𝑏2 )ℎ
A= 2

Example #1: Find the area of a triangle with a base of 10 cm and a height of 5
cm.

Solution:
1 1 1
A = 2 (b x h) = 2 (10 cm x 5 cm) = 2 (50 cm2) = 25 cm2

Example #2: Find the area of a parallelogram with the given measures: b= 8 m,
h = 11m
 Solution:
A=bxh = 8 m x 11 m = 88 m2

Example #3: Find the area of a trapezoid with the given measures: bases = 3
m and 6 m, h = 10 m

Solution:
(𝑏1 +𝑏2 )ℎ (3 𝑚+6𝑚)10 𝑚 9 𝑚 𝑥 10 𝑚 90 𝑚2
A= = = = = 45 m2
2 2 2 2

Practice Exercises
A. Find the area of the figures below.

1. 2. 3.
A = _________ A = _________ A = __________

4. 5.
A = __________ A = __________

B. Complete the table below. Use the correct formula to solve for the missing
part.
Plane Figure Base/ s Height Area
Parallelogram 18 cm 12 cm 1. __________
Triangle 2. __________ 7m 49 m2
Trapezoid 12 cm and 8 cm 10 cm 3. __________
Triangle 23 m 8m 4. __________
Parallelogram 12 cm 5. __________ 72 cm2

C. FIND THE HIDDEN MESSAGE

Find the area of the given plane figures, and then use the code to
unlock the message. Write the corresponding letter in the box.
1. A triangle with a base of 6 cm and a height of 3 cm
2. A parallelogram with a base of 10 m and a height of 7 m
3. A trapezoid with the bases 6 cm and 3 cm, and a height of 4 cm
4. A parallelogram with a base of 11 cm and a height of 6 cm
5. A triangle with a base of 12 m and a height of 9 m
6. A trapezoid with the bases 5 m and 6 m, and a height of 6 m
 Code:

MESSAGE:

Evaluation

Find the area of the given plane figures. Write your answer on the space
provided.
1. Triangle, base = 12 cm, height = 4 cm A = __________
2. Parallelogram, base = 22 m, height = 4 m A = __________
3. Trapezoid, bases = 7 m and 5 m, height = 5 m A = __________
4. Parallelogram, base = 16 cm, height = 8 cm A = __________
5. Triangle, base = 18 m, height = 9 m A = __________

Answer Key

Practice Exercises
A. 1. 120 cm2 2. 36 m2 3. 140 m2 4. 72 cm2 5. 72 cm2

B. 1. 216 cm2 2. 14 m 3. 100 cm2 4. 92 m2 5. 6 cm

C. MESSAGE
S T A Y S A F E
1 2 3 4 1 3 5 6

References
Mathematics 4, Learner’s Material pages 202- 212
Mathematics 4, Teacher’s Guide pages 268- 281