1. 10.1 Area of Polygons
Page 521

2. Essential Questions
 How do you know when to find
circumference or area?
 What strategies and formulas can you
use?
 How is surface area used in the real
world?
 How is the volume of a pyramid related
to the volume of a box?
 How is the volume of a cone related to
the volume of a cylinder?

3. Area and Perimeter
 Perimeter-The distance around a polygon
(the sum of the length of all sides)
 Area- The number of square units inside a
closed figure

5. Formulas
 Triangle: b x h or 1/2bh
2
 Rectangle: A = l x w
 Square: A = l x w or s2
 Parallelogram: A = b x h
 Trapezoid: (b1 +b2) x h or ½ (b1 +b2)x h
2

6. Area
 Steps:
1. Write the area formula
2. Substitute the values given
3. Answer

7. Area of a parallelogram
A=bxh
height 90º
base

8. What is the area of this parallelogram?
A=bxh
height 5 cm.
A=5x7
A = 35 cm2
base 7 cm.
Perimeter
P= 5 + 7 + 5 + 7 = 24 cm

9. What is the area of this parallelogram?
A=bxh
5 ft.
A=5x6
6 ft. A = 30 ft2
8 ft.
Perimeter
P= 6 + 8 + 6 + 8 = 28 ft

10. What is the area of this parallelogram?
12 m. A=bxh
A = 10 x 5
10 m. 5 m. A = 50 m2
Perimeter
P= 5 + 12 + 5 +12= 34 m

11. Area of a trapezoid
base 1 • Area =
(b1 +b2) x h
height
2
base 2

12. Area of a trapezoid
• Area =
(b1 +b2) x h
base 1 base 2 2
height

13. What is the area of this trapezoid?
• Area =
15 inches (b1 +b2) x h
2
• Area =
8 Inches 12
(15 +7) x 8
7 inches 2
Perimeter
P= 7 + 15 + 12 + 12= 46 in A= 88 in. sq.

14. GUIDED PRACTICE for Examples 1 and 2
2. A trapezoid with bases of 14 feet and 17 feet and a
height of 6 feet
1
A= (b + b2)h Write formula for area of a trapezoid.
2 1
1
A= (14 + 17)6 Substitute values for b1, b2 and h.
2
= 93 square feet Multiply.

15. What is the area of this trapezoid?
• Area =
25 (b1 +b2) x h
2
35 15 20 • Area =
cm
(20 +35) x 15
2
Perimeter A= 412.5 cm sq.
P= 35 + 25 + 20 + 25= 105 cm

16. How to find the area of a square
or rectangle.
Step 1 – Multiply the length times the
width. (A = l x w)
5
3 cm. x3
15 cm 2
Perimeter
5 cm.
P= 3 + 5 + 3 + 5= 16 cm

17. What is the area?
A=bxh
2 in.
2
6 in. x6
12 in. 2
Perimeter
P= 2 + 6 + 2 + 6 = 16 in

18. TRIANGLES
 Area formula for triangles is
A=bxh or ½ b (h)
 2
h
b

19. What is the area of this triangle?
Area = b x h
2
Area = 20 x 20
20 in
2
20 in A= 200 in. sq.

20. What is the area of this triangle?
Area = b x h
2
Area = 5 x 10
5 in 2
10 in A= 25 in. sq.

21. What is the area of this triangle?
Area = b x h
2
Area = 10 x 8
2
10 in
A= 40 in. sq.
8 in

22.  Find the area and perimeter:
Area = b x h
9 cm 12 cm
2 8
Area = 18 x 8
2
18 cm
A= 72 cm sq. P= 9 + 12 + 18 = 39 cm

23.  Find the area and perimeter:
Area = b x h
2
Area = 8 x 7
15 in
8 in 10 in
2
7 in A= 28 in. sq.
P= 10 + 15 + 7 = 32 in.