Circles

1
Circles
and
Circumference
2
Circle

• A circle is the set of all points that are the
  same distance from a given point called the
  center.

3
Center

• The given point from which all points on a circle
  are the same distance.

4
Circumference

• The distance around a circle.

5
Diameter

• The diameter of a circle is a line segment that
  joins any two points on the circle and passes
  through the center of the circle.

6
Radius

• The radius of a circle is a line segment joining
  the center of the circle and any point on the
  circle.

7
circumference
diameter
radius
diameter 2 times radius
of diameter
radius
8
Find the radius.
r d 2
8cm
r 8 2
r 4 cm
Find the diameter.
d 2r
6 yd
d 2?6
d 12 yd
9
The relationship of the circumference and the
diameter of a circle is called pi. The symbol
for pi is .
10
Circumference
Think of fact families
11
Circumference
WORDS The circumference of a circle is equal to
pi times its diameter or pi times twice its
radius.
Symbols
or
12
Circumference
Symbols
or
13
The circumference of a circle is a little more
than three times its diameter.
The circumference of a circle is a little more
than six times its radius.
14
Find the circumference.
Use .
8cm
15
Find the circumference.
Use .
4 ft
16
Find the circumference.
Use .
6 mm
6 x 6
17
Find the circumference.
Use .
7 mm
6 x 7