1. Angles

2. Angles – sides and vertex
When two rays or line segments meet at a point,
they form an angle at that point.
Each of the two rays or line segments are called sides.
The common endpoint is called the vertex. T S R
side
sides:
SR and RT
vertex: R
vertex
side

3. Naming Angles There are several ways to name this angle.
1) Use the vertex and a point from each side.
SRT or
TRS
vertex
side 1 T S R
The vertex letter R is always in the middle.
2) Use the vertex letter only. R
If there is only one angle at a vertex, then the angle can be named with that vertex.
3) Use a number. 1

4. Example 1 1) Name the angle in four ways. ABC CBA B 1
2) Identify the vertex and sides of this angle.
vertex:
Point B
sides:
BA and BC

5. Example 2 1) Name the angle in four ways. KLM MLK L 1
2) Identify the vertex and sides of this angle.
vertex:
Point L
sides:
LK and LM

6. Example 3 1) Name the angles. XWZ or ZWX XWY or YWX ZWY or YWZ 1 2
2) Identify the vertex and sides of this angle.
vertex:
Point W
sides:
WX, WY
and WZ

7. Example 4 1) Name all angles having O as their vertex. POR or ROPQ P R 1 2 O
POQ or
QOP
QOR or
ROQ 1 2
2) What are other names for ? 1
POQ or
QOP
3) Is there an angle that can be named ? O
No!

8. Try these 1. Name the vertex and side of the given angle
Name the given angles.