Transcript Angles - Lake Dallas Independent School District

Angles
Angles
• Angles have two sides that share a common endpoint
called a vertex of the angle.
• Angles are most commonly measured in degrees –
for example 90°, 175°
ANGLE
VERTEX
SIDE
Naming an Angle
• An angle is named by the letters on the angle.
Order IS IMPORTANT!!!
• This is angle PQR or RQP
• The point or vertex of the angle is always in
the middle
P
Q
R
Name the angle
C
CED or DEC
E
D
JLK or KLJ
L
J
K
Classifying Angles – 4 types
RIGHT ANGLE – an angle that is exactly 90°
ACUTE ANGLE – an angle that is less than 90°
OBTUSE ANGLE – an angle that is more than 90°
STRAIGHT ANGLE – an angle that is exactly 180°
D
E
C
36O
56O
F
28O
34O
26O
G
Name an angle within the figure that is an acute angle
Name an angle within the figure that is an obtuse angle
Name an angle within the figure that is a right angle
Name an angle within the figure that is a straight angle
B
A
Measuring Angles
• Angles are measured with a protractor
When measuring angles, place center of the protractor on the vertex.
Use
theone
TOPside
setof
ofthe
numbers
because0.the one side that
Make
sure
angle crosses
crossesthe
theother
0 hasside
the crosses
0 that isthe
on protractor.
the top.
See where
The measure of this angle is 50°
Themeasure
angle is 75°
What is the
of the angle?
You may have to turn the protractor to line up
the 0 with one side of the angle.
What is the measure of the
angle?
129°
What is the measure of WST?
155°
U
V
T
R
S
W
What is the measure of RSU?
86°
U
V
T
R
S
W