point a location line line segment ray a straight path that goes on forever in both directions. a...
TRANSCRIPT
Point A location
Line
Line segment
Ray
A straight path that goes on forever in both directions.
A straight path between the points, called its endpoints.
A straight path that goes on forever in one direction from an endpoint.
Geometry Terms
End Point
If we look around us, we will see angles everywhere.
Angles In Daily Life
To name an angle, we name any point on one ray, then the vertex, and then any point on the other
ray.
For example: ABC or CBA
We may also name this angle only by the single letter of the vertex, for example B.
A
BC
Review Naming an Angle
There are four main types of angles.
Straight angle
Right angle
Acute angle Obtuse angle
A
B C
A
B C
A
B C
BA C
Review Types f Angles
Right angle: An angle whose measure is 90 degrees.
Right Angle Acute AngleStraight Angle Obtuse Angle
Examples Of Right Angle
Examples Of Obtuse Angle
Acute angle: An angle whose measure is less than 90 degrees.
Right Angle Acute AngleStraight Angle Obtuse Angle
Examples Of Acute Angle
Straight angle: An angle whose measure is 180 degrees.
Right Angle Acute AngleStraight Angle Obtuse Angle
Examples Of Straight Angle
Lines in a plane
What can you say about these pairs of lines?
These lines cross, or
intersect.
These lines do not intersect.
They are parallel.
Angles
Angles are measured in degrees.
A quarter turn measures 90°.
It is called a right angle.
We label a right angle with a small square called a square corner.
90°
Angles
A half turn measures 180°.
This is a straight angle180°
Angles
A full turn measures 360°.360°
Adjacent AnglesTwo angles that have a common vertex and a common ray are called adjacent angles. “SIDE BY SIDE”
C
D
B
A
Common ray
Common vertex
Adjacent Angles ABD and DBC
Adjacent angles do not overlap each other.
D
EF
A
B
C
ABC and DEF are not adjacent angles
More examples of adjacent angles.
55º
35º
50º130º
80º 45º
85º20º
Missing Angles
Our learning objectives today•To calculate missing angles on a straight line, around a point and in a triangle.
What do you need to know?Angles in a triangle add up to.................
180°
Angles on a straight line add up to.......180°
Angles around a point add up to.............360°
Complementary Angles
Two angles are called complementary angles if the sum of their degree measurements equals
90 degrees.
Example: These two angles are complementary.
These two angles can be “put" together to form a right angle which is
complementary!
Supplementary AnglesTwo angles are called supplementary angles if the sum of their degree measurements equals
180 degrees.
Example: These two angles are supplementary.
These two angles can be “put" together to form a straight line!
Find the missing angle. You do not have a protractor.Use the clues in the pictures.
1.x
55
X=35
Find the missing angle. You do not have a protractor.Use the clues in the pictures.
2.165x
X=15
Calculate the missing straight line angle
69° 111°
Calculate the missing triangle angle
54°
89°
37°
Calculate the missing straight line angle
42°
103°35°