Grade 4 - Progress in Mathematics

Circles

10-4

A

E

D

B

C

F

G

A circle is named

by its center point.

The length of the diameter

is always twice the length

of the radius.

A diameter is a

special chord.

Use circle H.

1. Name six points on the circle.


2. Name five line segments
   that are radii.


3. Name three line segments
   that are chords. Which one
   is not a diameter?

K

H

N

L

J

M

I

A circle is a plane figure. All the points

on the circle are the same distance

from a given point, called the center.

Point Ais the center of circle A.

The parts of a circle have special names.

Any line segment with endpoints

at the centerof the circle and

onthe circle is a radius.

BEis a radius of circle B. BCand BD

are also radii (plural of radius) of circle B.

Any line segment that passes through

the center of the circle and has both

endpoints on the circle is a diameter.

CD is a diameter.

Any line segment with bothendpoints

onthe circle is a chord.

FG is a chord.

8204-6_332-333 10/4/07 8:05 AM Page 332