1. 8-1 Warm Up Problem of the Day Lesson Presentation
Perimeter & Area of Rectangles & Parallelograms
8-1
Warm Up
Problem of the Day
Lesson Presentation
Course 3

2. Course 3
8-1
Perimeter & Area of Rectangles & Parallelograms
Warm Up
Graph the line segment for each set of ordered pairs. Then find the length of the line segment.
1. (–7, 0), (0, 0)
2. (0, 3), (0, 6)
3. (–4, –2), (1, –2)
4. (–5, 4), (–5, –2)
7 units
3 units
5 units
6 units

3. Course 3
8-1
Perimeter & Area of Rectangles & Parallelograms
Problem of the Day
Six pennies are placed around a seventh so that there are no gaps. What figure is formed by connecting the centers of the six outer pennies?
regular hexagon

4. Course 3
8-1
Perimeter & Area of Rectangles & Parallelograms
Perimeter and Area of Rectangles and Parallelograms
Learn to find the perimeter and area of rectangles and parallelograms.
Course 3

5. Vocabulary 8-1 perimeter area
Course 3
8-1
Perimeter & Area of Rectangles & Parallelograms
Vocabulary
perimeter
area

6. 8-1 Perimeter & Area of Rectangles & Parallelograms
Course 3
8-1
Perimeter & Area of Rectangles & Parallelograms
Any side of a rectangle or parallelogram can be chosen as the base. The height is measured along a line perpendicular to the base.
Rectangle
Parallelogram
Height
Height
Side
Base
Base
Perimeter is the distance around the outside of a figure. To find the perimeter of a figure, add the lengths of all its sides.

7. 8-1 Perimeter & Area of Rectangles & Parallelograms
Course 3
8-1
Perimeter & Area of Rectangles & Parallelograms
Additional Example 1A: Finding the Perimeter of Rectangles and Parallelograms
Find the perimeter of the figure. 5 14
P =
Add all side lengths.
= 38 units
or P = 2b + 2h
Perimeter of rectangle.
Substitute 14 for b and 5 for h.
= 2(14) + 2(5)
= = 38 units

8. 8-1 Caution! Perimeter & Area of Rectangles & Parallelograms
Course 3
8-1
Perimeter & Area of Rectangles & Parallelograms
When referring to the measurements of a rectangle, the terms length (l) and width (w) are sometimes used in place of base (b) and height (h). So the formula for the perimeter of a rectangle can be written as
P = 2b + 2h = 2l + 2w = 2(l + w).
Caution!

9. 8-1 Perimeter & Area of Rectangles & Parallelograms
Course 3
8-1
Perimeter & Area of Rectangles & Parallelograms
Additional Example 1B: Finding the Perimeter of Rectangles and Parallelograms
Find the perimeter of the figure. 20 16
P =
Add all side lengths.
= 72 units

10. 8-1 Perimeter & Area of Rectangles & Parallelograms
Course 3
8-1
Perimeter & Area of Rectangles & Parallelograms
Check It Out: Example 1A
Find the perimeter of the figure. 6 11
P =
Add all side lengths.
= 34 units
or P = 2b + 2h
Perimeter of rectangle.
Substitute 11 for b and 6 for h.
= 2(11) + 2(6)
= = 34 units

11. 8-1 Perimeter & Area of Rectangles & Parallelograms
Course 3
8-1
Perimeter & Area of Rectangles & Parallelograms
Check It Out: Example 1B
Find the perimeter of the figure. 5 13
P =
Add all side lengths.
= 36 units

12. Course 3
8-1
Perimeter & Area of Rectangles & Parallelograms
Area is the number of square units in a figure. A parallelogram can be cut and the cut piece shifted to form a rectangle with the same base length and height as the original parallelogram. So a parallelogram has the same area as a rectangle with the same base length and height.

13. 8-1 Helpful Hint Perimeter & Area of Rectangles & Parallelograms
Course 3
8-1
Perimeter & Area of Rectangles & Parallelograms
The formula for the area of a rectangle can also be written as A = lw.
Helpful Hint

14. Additional Example 2A: Using a Graph to Find Area
Course 3
8-1
Perimeter & Area of Rectangles & Parallelograms
Additional Example 2A: Using a Graph to Find Area
Graph the figure with the given vertices. Then find the area of the figure.
(–1, –2), (2, –2), (2, 3), (–1, 3)
Area of a rectangle.
A = bh
Substitute 3 for b and 5 for h.
A = 3 • 5
A = 15 units2

15. 8-1 Caution! Perimeter & Area of Rectangles & Parallelograms
Course 3
8-1
Perimeter & Area of Rectangles & Parallelograms
The height of a parallelogram is not the length of its slanted side. The height of a figure is always perpendicular to the base.
Caution!

16. Additional Example 2B: Using a Graph to Find Area
Course 3
8-1
Perimeter & Area of Rectangles & Parallelograms
Additional Example 2B: Using a Graph to Find Area
Graph the figure with the given vertices. Then find the area of the figure.
(0, 0), (5, 0), (6, 4), (1, 4)
Area of a parallelogram.
A = bh
Substitute 5 for b and 4 for h.
A = 5 • 4
A = 20 units2

17. 8-1 Perimeter & Area of Rectangles & Parallelograms
Course 3
8-1
Perimeter & Area of Rectangles & Parallelograms
Check It Out: Example 2A
Graph the figure with the given vertices. Then find the area of the figure.
(–3, –2), (1, –2), (1, 3), (–3, 3) x y
(–3, –2)
(1, –2)
(1, 3)
(–3, 3) 4 5
Area of a rectangle.
A = bh
Substitute 4 for b and 5 for h.
A = 4 • 5
A = 20 units2

18. 8-1 Perimeter & Area of Rectangles & Parallelograms
Course 3
8-1
Perimeter & Area of Rectangles & Parallelograms
Check It Out: Example 2B
Graph the figure with the given vertices. Then find the area of the figure.
(–1, –1), (3, –1), (5, 3), (1, 3)
(5, 3) x y
(–1, –1)
(3, –1)
(1, 3) 4
Area of a parallelogram.
A = bh
Substitute 4 for b and 4 for h.
A = 4 • 4
A = 16 units2

19. Additional Example 3: Finding Area and Perimeter of a Composite Figure
Course 3
8-1
Perimeter & Area of Rectangles & Parallelograms
Additional Example 3: Finding Area and Perimeter of a Composite Figure
Find the perimeter and area of the figure. 6 6 3 3 6 5 5
The length of the side that is not labeled is the same as the sum of the lengths of the sides opposite, 18 units.
P =
= 52 units

20. Additional Example 3 Continued
Course 3
8-1
Perimeter & Area of Rectangles & Parallelograms
Additional Example 3 Continued 6 6 3 3 6 5 5
A = 6 • • • 5
Add the areas together. =
= 72 units2

21. 8-1 Perimeter & Area of Rectangles & Parallelograms
Course 3
8-1
Perimeter & Area of Rectangles & Parallelograms
Check It Out: Example 3
Find the perimeter of the figure.
The length of the side that is not labeled is 2. 2 4 6 7 7 2 6 2
P = ?
= 42 units 4

22. Check It Out: Example 3 Continued
Course 3
8-1
Perimeter & Area of Rectangles & Parallelograms
Check It Out: Example 3 Continued 2
Find the area of the figure. 4 6 7
Add the areas together.
A = 2 • • • • 2 7 2 2 6 = 2 2
= 38 units2 2 6 4 2 4 7 2 2 + + +

23. 8-1 Perimeter & Area of Rectangles & Parallelograms
Course 3
8-1
Perimeter & Area of Rectangles & Parallelograms
Lesson Quiz: Part I
1. Find the perimeter of the figure.
44 ft
12 ft
5 ft
5 ft
4 ft
5 ft
5 ft
12 ft

24. 8-1 Perimeter & Area of Rectangles & Parallelograms
Course 3
8-1
Perimeter & Area of Rectangles & Parallelograms
Lesson Quiz: Part II
2. Find the area of the figure.
108 ft2
12 ft
5 ft
5 ft
4 ft
5 ft
5 ft
12 ft

25. 8-1 Perimeter & Area of Rectangles & Parallelograms
Course 3
8-1
Perimeter & Area of Rectangles & Parallelograms
Lesson Quiz: Part III
Graph the figure with the given vertices and find its area.
3. (–4, 2), (6, 2), (6, –3), (–4, –3)
50 units2

26. 8-1 Perimeter & Area of Rectangles & Parallelograms
Course 3
8-1
Perimeter & Area of Rectangles & Parallelograms
Lesson Quiz: Part IV
Graph the figure with the given vertices and find its area.
4. (4, –2), (–2, –2), (–3, 5), (3, 5)
42 units2