Page 146 - Math Course 3 (Book 2)

Circles: Parts and Circumference
Mo. 11

Lesson 1 radius
Any segment with endpoints that are the center and
a point on the circle is a radius.

KEY CONCEPTS: CD, CB and CE A B

1. Identify and use parts of circles. are radii of the radius
2. Find circumference, diameter, and radius circle
of a circle.
3. Solve problems involving the circumference C
of a circle. F

D
MO. 11 - L1a
E

Parts of a Circle diameter

A chord that passes through the center is a
diameter of the circle.

Vocabulary A-Z A B
BE is a
Let us learn some vocabulary diameter

circle C
A circle is the locus of all points in a plane F
equidistant from a given point called the center
of the circle. diameter D
E
center
A circle is usually named by its center point. The
figure shows circle C, which can be written as C. Let’s Begin

Identify Parts of a Circle

C
Example

Name the circle.
B
chord
Any segment with both endpoints that are on the A
circle is a chord of the circle.

A B E

Chord
C
C D
F
Answer The circle has its center at E,
AF and BE D so it is named circle E, or ⊙E.
are chords.
E
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