math iv finding the area of an irregular figures
TRANSCRIPT
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