1. Objective
Apply formulas for perimeter, area, and circumference to composite figures.

2. The perimeter, P ,is the distance around a polygon.
The area, A, is the surface inside a polygon.
Perimeter is expressed in linear units, such as inches (in.) or meters (m).
Area is expressed in square units, such as square centimeters (cm2).
Remember!

3. Remember that the base and height of a triangle are always
perpendicular to each other.
Below are three examples showing the base and height.

4. Find the exact perimeter and area of the composite figure.

5. First we need to find a few more dimensions

6. What would this dimension be?

7. How about this dimension?

8. And this dimension?
3 m
3 m
4 m
4 m ?
6 m
4 m

9. Now for this dimension?
Use so or
3 m
3 m ?
4 m
4 m
4 m
6 m
4 m

10. We need one more dimension to find the perimeter. Do you know where?

11. How do we find this dimension?

12. Something is wrong with the last
dimension.
Find the error!
3 m
3 m
4 m
4 m
4 m
6 m
4 m

13. We only want half a circle
How do we change this?

14. Now that we have all of our dimensions let’s find the perimeter!

15. Add all the distances along the outside of the figure.
3 m
3 m 4
4 m
4 m 6
6 m 4
4 m + + + + P=

16. Simplify
3 m
3 m 4
4 m
4 m 6
6 m 4
4 m
P= m

17. Now let’s find the area! 3 m 3 m 4 4 m 4 m 6 6 m 4 4 m
Get rid of all the excess information for a minute
3 m
3 m 4
4 m
4 m 6
6 m 4
4 m

18. This figure is made of 3 shapes.
Can you identify them?
Half circle
Triangle
Rectangle

19. Find the area of each shape.
This is the area formula for a full circle.
What do we need to do to get the area of a half circle?
Half circle
Triangle
Rectangle

20. the area of the composite figure?
What would we do to find
the area of the composite figure?
Half circle
Triangle
Rectangle + +

21. Go back to our figure with
all the dimensions
Now let’s fill in numbers for the variables
What is the radius of the half circle?
What is the length of the rectangle?
What is the width of the rectangle?
What is the base of the triangle?
What is the height of the triangle?
3 m
3 m
Put this into your calculator
and give me the area of the
composite figure.
(give answer to the
nearest tenth) 4
4 m
4 m
What are we forgetting
on our answer? 6
6 m 4
4 m + +

22. Jokes
What has four wheels and flies?
A garbage truck!
What kind of car does Mickey Mouse's wife drive?
A Minnie van!