Download Angles, Triangles and Quadrilaterals

Lesson 1: Angle Problems and
Solving Equations
Angles
 A shape formed by two rays sharing a
common endpoint; contains two rays
and a vertex
vertex—point common to two
rays of a triangle or two sides
of a polygon
ray
vertex
ray—has one endpoint and
goes infinitely in one direction
ray
Naming Angles
An angle is named by three letters.
The vertex must be in center.
A
1
B
C
Types of Angles
 Acute angle: An angle whose
measure is greater than zero degrees
and less than 90 degrees
Which angles are not acute?
4
1
3
2
5
Types of Angles
 Right angle: Angle that measures
90 degrees
Which angle is a right angle?
4
1
3
2
5
Types of Angles
 Obtuse angle: One angle measures
greater than 90 degrees and less
than 180 degrees
Which angle is an obtuse angle?
4
1
3
2
5
Straight Angle
 Straight angle: A line that goes
infinitely in both directions and
measures 180 degrees
Which is not a straight angle?
1
2
This is a ray. It only
goes in one direction.
Adjacent angles are “side by side” and share a
common ray.
15º
45º
These are examples of adjacent angles.
80º
45º
35º
55º
130º
85º
20º
50º
These angles are NOT adjacent.
100º
50º
35º
35º
55º
45º
When 2 lines intersect, they
make vertical angles.
75º
105º
105º
75º
Vertical angles are opposite one another.
75º
105º
105º
75º
Vertical angles are opposite one another.
75º
105º
105º
75º
Vertical angles are congruent (equal).
150º
30º
30º
150º
Supplementary angles add up to
180º.
40º
120º
60º
Adjacent and Supplementary
Angles
140º
Supplementary Angles
but not Adjacent
Complementary angles add up
to 90º.
30º
40º
50º
60º
Adjacent and Complementary
Angles
Complementary Angles
but not Adjacent