Calculate the area of irregular shapes using square units
Objectives
Student will be able to:
calculate the area of irregular shapes using square units.
Introduction
Not every shape has a formula for area. For example, a landscaper might be designing an irregularly shaped flower bed. The landscaper can still find the area of the shape if she needs to know how much mulch to buy to cover it.
She would determine how many square units cover the irregular region. Then she would write the number of square units in terms of the measurement units squared. The square units can use any measurement unit, such as inches, millimeters, or meters.
This is a drawing of Jubilee's swimming pool. Find the area of her pool.
one square unit =
STEP 1:
Divide the pool shape into regular shapes. In this case, the pool shape can be divided into two rectangles.
STEP 2:
Count the squares in each shape. There are 2 squares in one rectangle and 3 squares in the other.
STEP 3:
Add the areas of the two rectangles.
STEP 4:
Label the answer in square units.
Examples
1.
What is the area of this irregular figure?
one square unit =
Divide the shape. Make 2 rectangles (top and bottom). Count the number of units in each rectangle (3 units). Note that 4 single units are left over (middle squares).
Add.
The area is
2.
Find the area of this irregular shape.
one square unit =
Divide the shape. Make 2 rectangles. Count the number of units in each rectangle.
5 units
4 units
Now add the number of units in each rectangle. Remember to include the measurement units squared in your answer.
The area is
Try Together
Calculate the area of these irregular figures. Show all work.
1.
What is the area?
one square unit =
Check student's work.
2.
Find the area.
one square unit =
Check student's work.
Please evaluate the student's answers:
Excellent
Good
Okay