Embed Size (px)
Citation preview
10.1 Area of Polygons
Page 521
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?
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
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
Area
Steps:1. Write the area formula 2. Substitute the values given3. Answer
Area of a parallelogram
height
base
A = b x h
90º
What is the area of this parallelogram?
base 7 cm.
height 5 cm.A = b x h
A = 5 x 7
A = 35 cm2
PerimeterP= 5 + 7 + 5 + 7 = 24 cm
What is the area of this parallelogram?
6 ft.
5 ft.
8 ft.
A = b x h
A = 5 x 6
A = 30 ft2
PerimeterP= 6 + 8 + 6 + 8 = 28 ft
What is the area of this parallelogram?
5 m.10 m.
12 m. A = b x h
A = 10 x 5
A = 50 m2
PerimeterP= 5 + 12 + 5 +12= 34 m
Area of a trapezoid
• Area =
(b1 +b2) x h
2
base 1
height
base 2
Area of a trapezoid
• Area =
(b1 +b2) x h
2 base 1 base 2
height
What is the area of this trapezoid?
15 inches
8 Inches
7 inches
• Area =
(b1 +b2) x h
2
A= 88 in. sq.
12• Area =
(15 +7) x 8
2 PerimeterP= 7 + 15 + 12 + 12= 46 in
GUIDED PRACTICE for Examples 1 and 2
Substitute values for b1, b2 and h.
Multiply.
A = (b1 + b2)h1
21
2A = (14 + 17)6
= 93 square feet
Write formula for area of a trapezoid.
2. A trapezoid with bases of 14 feet and 17 feet and a height of 6 feet
What is the area of this trapezoid?
A= 412.5 cm sq.
25
15 20 cm
35
• Area =
(b1 +b2) x h
2 • Area =
(20 +35) x 15
2 PerimeterP= 35 + 25 + 20 + 25= 105 cm
How to find the area of a squareor rectangle.
3 cm.
5 cm.
Step 1 – Multiply the length times the width. (A = l x w)
53x
15 cm2
PerimeterP= 3 + 5 + 3 + 5= 16 cm
What is the area?
2 in.
6 in.
26x
12 in.2
A = b x h
PerimeterP= 2 + 6 + 2 + 6 = 16 in
TRIANGLES Area formula for triangles is
A = b x h or ½ b (h) 2
h
b
What is the area of this triangle?
20 in
20 in
Area = b x h
2
A= 200 in. sq.
Area = 20 x 20
2
What is the area of this triangle?
5 in
10 in
Area = b x h
2
A= 25 in. sq.
Area = 5 x 10
2
What is the area of this triangle?
10 in
8 in
Area = b x h
2
A= 40 in. sq.
Area = 10 x 8
2
Find the area and perimeter:
9 cm
18 cm
12 cm8
9 cm
18 cm
12 cm
A= 72 cm sq. P= 9 + 12 + 18 = 39 cm
Area = b x h
2
Area = 18 x 8
2
Find the area and perimeter:
10 in 15 in
7 in
8 in
A= 28 in. sq.P= 10 + 15 + 7 = 32 in.
Area = b x h
2 Area = 8 x 7
2
