FINDING THE AREA

OF AN IRREGULAR

FIGURE

To find the area of an irregular figure, the first thing to do is to divide the irregular shape to regular shapes that you can recognize such as rectangle and square.

When you done dividing, find the area of these individual shapes and add all answers.

EXAMPLES:

3cm

12 cm

3cm

12 cm

Area of SquareA = s2

A = 3cm x 3cm

A = 9 sq cm

Area of RectangleA = l x w

A = 3cm x 12cmA = 36 sq cm

9 sq cm36 sq cm

A = 45 sq cm

Add:

2cm 4cm

20cm

20cm

4cm

20cm

2cm

4cm

4cm

20cm

20cm

2cmArea of Rectangle:

A = l x w

A = 20cm x 2cmA = 40 sq

cm

4cm

20cm

Area of rectangle: A = l x w A = 4cm x

20cm A = 80 sq cm

4cm

Area of square:A = s2

A = 4cm x 4cmA = 16 sq cm

Add:

40 sq cm80 sq cm16 sq cm

A = 136 sq cm

GENERALIZATION

There are 3 steps in finding the area of an irregular figure.1. DIVIDE irregular figure to regular shapes.

2. FIND THE AREA of each shapes.

3. ADD all the answers.

EXERCISE Find the area of the given

irregular figures.

8cm

5cm6cm

2cm3cm

12cm

4cm

8cm 6cm

5cm 4cm

3cm2cm

12cm