### Circles – Lines and Segments

```Circles – Segments and
Circumference
Circle – The set of all
points in a plane a
given distance from a
given point (the
center). Circles are
named by their center
point.
Concentric circles – Circles
in the same plane with the
same center.
A
B
C
Circles – Segments and
Circumference
with endpoints that are
the center of a circle
and a point on the
circle.
Chord – A segment with
two endpoints on the
circle.
Diameter – A chord that
passes through the
center.
F
D
diameter
chord
A
E
C
B
Circles – Segments and
Circumference
Pi (  ) – An irrational number that is
defined as the ratio of the
circumference to the diameter of a
circle. (C/d = )
Circumference – The distance around a
circle. Represented by either:
C =  • d or C = 2 •  • r
a. Name the circle.
b. Name a radius of the circle.
c. Name a chord of the circle.
d. Name a diameter of the circle.
Circle M has diameters
a. If BG = 25, find MG.
b. If DM = 29, find DN.
c. If MF = 8.5, find MG.
The diameters of
, and
are 5 inches,
9 inches, and 18 inches respectively.
a. Find AC.
b. Find EB.
a. Find C if r = 22 centimeters.
b. Find C if d = 3 feet.