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Chapter 1
Exploring Geometry:
Points, Lines, and
Angles in the Plane
Section 3
Copying and Bisecting
Angles
Objectives:
Students will be introduced
to angles and be able to
draw and bisect angles
using a compass.
Angle
An angle () is a figure formed from two
rays (called the sides of the angle) with the
same endpoint (called the vertex of the
angle).
Side XW
W
X
Vertex
Point X
Chapter 1
Y
Side XY
Section 3 - Copying and Bisecting
Angles
2
Naming an Angle
A
B
1
C
 If there is only one angle at a vertex, you
can use a single letter to name the vertex
of the angle.
B
 If there is more than one angle at a vertex,
name the angle using three letters, with the
middle letter being the vertex.
ABC or CBA
Vertex
 An angle can also be named by a number.
1
Chapter 1
Section 3 - Copying and Bisecting
Angles
3
Example 1
1. Name the angle in as many ways as
possible.
Answer: R, 3, QRS, or SRQ
2. Name the sides and the vertex of the
angle. Answer: Sides - RQ and RS
Vertex - Point R
Q
R
3
S
Chapter 1
Section 3 - Copying and Bisecting
Angles
4