Lesson 29
Area of a Combined Figure
Get the Idea
• Sometimes, you need to find the area of a
figure that is not a common shape. You can
often do this by dividing that figure into
familiar shapes, such as triangles, rectangles
or circles.
• The formulas for finding the area of triangles,
rectangles or circles will be provided for you
on the NJAsk Reference Sheet
Example 1
• This is the floor plan of the dining room n a
new house. The dining room is rectangular
with another rectangular area near one end.
How many square feet of wood flooring would
be needed to completely cover the floor in
this room?
12 ft
15 ft
12 ft
18 ft
Strategy
• Divide the figure into two shapes. Then find
the area of each.
12 ft
12 ft
12x12
12 ft
6x15
15 ft
6 ft
Total: 18 ft
• 12 x 12= 144 and 6x15= 90. 144+90= 234 sq.ft
Example 2
• This is a sketch of a park near McHenry
School. Find the area of the park.
30 ft
50 ft
50 ft
50 ft
• How would I cut this shape up?
How we cut it up…
• Divide the figure into two shapes. Then find
the area of each.
½(50 x30)
50 ft
30 ft
50 x50
50 ft
50 ft
• Square: 50x50= 2500
• Triangle: ½(50x30)= ½ (1500)= 750
• 2500+750 = 3250 sq ft.
One more together
• What is the total area of the figure below?
10m
10m
10m
• Draw a line to divide the figure above into a ¼
circle and a square.
• How do I find the area of a ¼ circle?
• What do I do to find the total area of the shape?