Download Measuring Angles and Segments

Definition
Angle: formed by two rays with
a common endpoint (“vertex”).
A
C
B
Practice
Name the angle below in four ways.
The name can be the number inside of the angle: 3.
*The name can be the vertex of the angle: G.
The name can be a point on one side, the vertex, and a point
on the other side of the angle: AGC, CGA.
Types of Angles
1. Acute
Less than 90°
2. Right
Exactly 90°
3. Obtuse
Greater than 90°, but
less than 180°
Types of Angles
4. Straight
Exactly 180°
5. Reflex
Greater than 180
but less than 360
Definition
Congruent Angles: angles with the same measure
Angle Addition Postulate
1-8: If point B is in the interior of AOC, then
mAOB + mBOC = mAOC
B
A
O
C
Practice
mHAT = 50 and mHAM = 125. What is the mMAT?
T
M
A
H
Practice
Suppose that m
m
1+m
1 = 42 and m ABC = 88. Find m
2 = m ABC
42 + m
2 = 88
m
2 = 46
2.
Angle Pairs
1. Vertical Angles: two angles whose sides are opposite
rays
1 and 3 are vertical angles, and 2 and 4 are
vertical angles.
2.
Adjacent Angles: two coplanar angles with a
common side, a common vertex, and no common
interior points.
1 and 2 are adjacent angles
Angle Pairs
3. Complementary Angles: two angles whose measures
have a sum of 90.
4. Supplementary Angles: Two angles whose measures
have a sum of 180.
In the diagram, these angles are supplementary:
1 and 2,
2 and 3,
3 and 4,
and 4 and 1.
Homework
Measuring Angles in
Student Practice Packet
(Page 6, #1-13)