Transcript Geometry: Introduction to Angles

Introduction to Angles
Complementary and Supplementary
Lines, Rays, and Angles
A line goes forever in both directions.
It is perfectly straight, and never ends.
A ray goes forever in one direction.
It has one endpoint.
An angle is two rays that share
an endpoint.
Parts of an Angle
• The point where the rays intersect is
called the vertex of the angle.
• The two rays are called the sides of the
angle.
Naming Angles
• Use the vertex and a point from each ray to
name the angle. The vertex must be the
middle letter. A
ABC
B
C
Sometimes we put this symbol
in front of an angle:
CBA
Vertexes and Sides
Complementary Angles
• Two angles are called complementary angles
if the sum (add) of their degree
measurements equals 90 degrees.
• Complementary Angles make a Right Angle.
Example:
Complementary Angles
Supplementary Angles
• Two angles are called supplementary angles
if the sum of their degree measurements
equals 180 degrees.
• Supplemental Angles make a Straight Line.
Example:
Supplementary Angles
Find the complementary and
supplementary angles for each.
Use half sheet of paper.
1) 73
2) 40
3) 29
4) 87
5) 56
6) 13