The document defines key terms related to circles: - A circle is the set of all points in a plane that are an equal distance from the center. - The radius is the distance from the center to any point on the circle. - The diameter is the distance across the circle through the center. - The circumference is the distance around the entire circle.

1. 10.4
Circumference and
Area of a Circle
March 17,
2011

3. A circle is
the set of all
points in a plane
that are equal
distance from
the center.

4. A circle is
the set of all
points in a plane
that are equal
distance from
the center. The radius, r,
is the distance
from the center to
any point on the
circle.

5. A circle is The diameter,
the set of all d, is the distance
points in a plane across the circle
that are equal through the
distance from center.
the center. The radius, r,
is the distance
from the center to
any point on the
circle.

6. A circle is The diameter,
the set of all d, is the distance
points in a plane across the circle
that are equal through the
distance from center.
the center. The radius, r,
is the distance The distance
from the center to around the circle is
any point on the called the
circle. circumference.

7. The
A circle is The diameter, ratio of the
the set of all d, is the distance circumference to
points in a plane across the circle the diameter is
that are equal through the known as pi, π.
distance from center. 3.14159 ... or
the center. The radius, r, 22/7
is the distance The distance
from the center to around the circle is
any point on the called the
circle. circumference.

8. The
A circle is The diameter, ratio of the
the set of all d, is the distance circumference to
points in a plane across the circle the diameter is
that are equal through the known as pi, π.
distance from center. 3.14159 ... or
the center. The radius, r, 22/7
is the distance The distance
from the center to around the circle is
any point on the called the
circle. circumference.