Download 1-4 Angle Measure

Notes #2 (1.4)
1.4 Angles Measure
Standard 1.0 Students demonstrate
understanding by identifying and giving
examples of undefined terms…
Objective:
Measure and classify angles
Ray: is a part of a line, it has an endpoint
(starting point) and extends indefinitely
G
F
Named EF, or EG
E
Q
P
P
R
Opposite Rays by definition are two collinear rays with a common endpoint
Angle
• An angle is formed by two non-collinear rays
(called the sides) with the same initial point
(called the vertex)
C
Vertex: point A
Ray
(Side)
B
A
Ray (Side)
Vertex
Sides: AB, and AC
Naming Angles
There are three ways to name angles
1. By using the vertex
A
2. By using the points
on the angle
C
BAC CAB
4
A
B
3. By using the number
inside the angle
4
Interior and Exterior of Angles
An angle divides a plane into 3 distinct parts. On, In, or Outside
ON
M
Points A, D, and E lie _____________
the angle
IN
Points C and B lie _____________
of the angle
A
C
F
D
G
B
E
OUTSIDE
Points F and G lie _____________
of the angle
Example 1 p. 32
Angles and Their Parts
W
X
Name all the angles that have
W as a vertex
Name the side of <1
2
1
3
5
Z
Write another name for <WYZ
V
4
Y
Classwork #3
Pg. 36 (9-23)odd
Homework #3
Pg. 36 (10-24)even
Notes #2 (1.4) continues
1.4 Angles Measure
Standard 1.0 Students demonstrate
understanding by identifying and giving
examples of undefined terms…
Objective:
Measure and classify angles
Identify and use congruent angles and
the bisector of an angle
Protractor
It has two scales running
from 0 to 180 degrees in
opposite directions
Align the 0 on either
side of the angle
Since QP is aligned
w/ 0 the other side
of the angle can be
measured at 65
degrees
The center point
of the protractor
is on the vertex
Classifying Angles
90 < m C < 180
Congruent Angles
Congruent Angles: are angles with the same measure
or degree
<A ~
= <B
m<A = m<B
Angle congruence looks like this…
D
B
A
C
Example
In the figure, ABC  DBF . If
and mDBF  8x 14.
Find the measurements of
A
C
B
D
F
mABC  6x  2
ABC  DBF
Angle Bisector: a ray that divides an angle into two
congruent angles
A
Angle Addition When a line divides an angle into two smaller angles
Then the sum of the smaller angles equals the larger angle
m< RSP + m<PST = m<RST
R
P
S
T
Classwork #4
Pg. 35 (1-8)no 6
Homework #4
Pg. 39 (13-20)