Do Now 4/16/13

1
Do Now 4/16/13

• Copy HW in your planner.
• Text p. 362, 1-24 all, 27, 32, 33
• In your notebook, define in your own words the
  following terms circumference, radius,
  diameter, center, and perimeter.
• Be ready to finish Cumulative Test Chapters 1-8
  from yesterday.

2
Objective

• SWBAT find the perimeter of a polygon and the
  circumference of a circle.

3
Section 9.1 Perimeter and Circumference
Perimeter

• the distance around a geometric figure

Circumference
the distance around a circle
4
Perimeter

• To find the perimeter P of a polygon, you can add
  the lengths of its sides.

8 m
12 m
25 cm
25 cm
14 ft
10 m
9 m
15 cm
18 ft
6 m
P 2l 2w
P 25 25 15
P 9 12 8 10 6
P (2 18) (2 14)
P 65 cm
P 45 m
P 36 28
P 64 ft
5
Circumference

To find the circumference of a circle, multiply the diameter by pi ( ). Circumference d Circumference 2 r
Circumference
Radius
Diameter
Circumference
6
Try It Out!!

• Find the circumference of the following circles.
  
• A).

B).
3 m
4 m
7
Working with Circumference

• Lily is drawing plans for a circular fountain.
  The circumference of the fountain is 63 ft. What
  is the approximate diameter?

8

• Find the distance around the figure.

Break the figures apart into simple shapes
circles, rectangles, squares, or triangles. Find
the distance around each part.
15 m
35 m
Distance around outside sides of rectangle
Distance around semi-circles
Total
35 m 35 m 47.1 m
35 m 35 m
117.1 m
9

• Find the distance around the figure.

Break the figures apart into simple shapes
circles, rectangles, squares, or triangles. Find
the distance around each part.
8 ft
Total
8 ft 8 ft 8 ft 8 ft 12.56 ft
Distance around semi-circle
Distance around outside sides of triangle
Distance around outside sides of square
8 ft 8 ft
8 ft 8 ft
44.56 ft
10

• The foul poles down the 1st and 3rd base lines
  on a baseball field are 250 feet from home plate.
  Find the distance around the outside of the
  field.

Break the figures apart into simple shapes
circles, rectangles, squares, or triangles. Find
the distance around each part.
Distance around quarter-circle
Total
1st 3rd base foul lines
250 ft 250 ft 392.5 ft
250 ft 250 ft
892.5 ft
11
24
Homework
Text p. 362, 1-24 all, 27, 32, 33