Geometry: Perimeter and Area

1
Four families traveled from different places to
vacation together at a lake. The Deweys drove
210 miles. The Webers drove 50 miles less than
the Deweys drove. The Golds drove 100 miles more
than the Webers drove. The Stones drove 110
miles more than the Webers drove. The drawing
shows the gas mileage for each family's car. How
many gallons of gas did each family use to get to
the lake? (Round answers to the nearest tenth.)
2
Trip to the Lake

• The Deweys used 10.5 gallons of gas.The Webers
  used 10.7 gallons of gas.The Golds used 10.8
  gallons of gas.The Stones used 9 gallons of gas.

3
Geometry Perimeter and Area

• Lesson 6-8
• Find the perimeter and area of figures

4
Perimeter

• The distance around a figure.
• One way to find the perimeter of a figure is to
  add the length of all the sides.
• When finding the perimeter of a rectangle we use
  a common formula.

5
Perimeter of a Rectangle

• P 2L 2W

L
W
6
Perimeter of a Rectangle

• P 2L 2W
• 2(15) 2(4)
• 30 8
• P 38cm

L 15 cm
W 4cm
7
Your Turn
2 ft
18 ft

• P 2L 2W
• 2(18) 2(2)
• 36 4
• P 40 ft

8
Find the Perimeter of an Irregular Figure

• Add the length of the sides
• 2.4 2.4 1.6
• 6.4 cm

2.4 cm
2.4 cm
1.6 cm
9
Find the Perimeter of a Square

• P 4s
• S side of the square
• P 4(12)
• P 48 in

12 in
10
Area

• The measure of the surface enclosed by the
  figure.
• To find the area of a rectangle we use this
  common formula.
• A L x W

11
Find the Area of a Rectangle

• A L x W

L
W
12
Find the Area of a Rectangle

• A L x W
• A 18 x 23
• A 414 ft

2
L 18ft
Units for area are always squared!!!
W 23 ft
13
Find the area of a Square
2

• Formula A S
• Which means to multiply s x s
• A 11
• A 11 x 11
• A 121 in

2
11 in
2
14
Lets Practice

• Lesson 6-8 Page 579
• 1-3 and 4-12 evens

15
Homework

• Lesson 6-8 2-14 evens
• Make sure you read the directions, for some
  questions you should find area and perimeter.
  You should have two answers for some questions!