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Students learn to measure and classify angles.
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You will learn to measure, draw, and classify angles.
1) Degrees2) Protractor3) Right Angle4) Acute Angle5) Obtuse Angle
Angle MeasureAngle Measure
In geometry, angles are measured in units called _______.degrees
Angle MeasureAngle Measure
In geometry, angles are measured in units called _______.degrees
The symbol for degree is °.
Angle MeasureAngle Measure
In geometry, angles are measured in units called _______.degrees
The symbol for degree is °.
Q
P
R
75°
In the figure to the right, the angle is 75 degrees.
In notation, there is no degree symbol with 75because the measure of an angle is a real number with no unit of measure.
m PQR = 75
Angle MeasureAngle Measure
Postulate 3-1
Angles Measure Postulate
For every angle, there is a unique positive number between __ and ____ called the degree measure of the angle.
B
A
C
n°
Angle MeasureAngle Measure
Postulate 3-1
Angles Measure Postulate
For every angle, there is a unique positive number between __ and ____ called the degree measure of the angle.
B
A
C
n°
0
Angle MeasureAngle Measure
Postulate 3-1
Angles Measure Postulate
For every angle, there is a unique positive number between __ and ____ called the degree measure of the angle.
B
A
C
n°
0 180
Angle MeasureAngle Measure
Postulate 3-1
Angles Measure Postulate
For every angle, there is a unique positive number between __ and ____ called the degree measure of the angle.
B
A
C
n°
0 180
m ABC = nand 0 < n < 180
Angle MeasureAngle Measure
J
H
G
SQ R
m SRQ =
Find the measurement of:
m SRJ =
m SRG =
m QRG =
m GRJ =
m SRH
Angle MeasureAngle Measure
J
H
G
SQ R
m SRQ =
Find the measurement of:
m SRJ =
m SRG =
m QRG =
m GRJ =
180
45
150
70
180 – 150= 30
150 – 45= 105
m SRH
Angle MeasureAngle Measure
Use a protractor to draw an angle having a measure of 135.
Angle MeasureAngle Measure
Use a protractor to draw an angle having a measure of 135.
1) Draw AB
A B
Angle MeasureAngle Measure
Use a protractor to draw an angle having a measure of 135.
1) Draw AB
2) Place the center point of the protractor on A. Align the mark labeled 0 with the ray.
A B
Angle MeasureAngle Measure
Use a protractor to draw an angle having a measure of 135.
1) Draw AB
2) Place the center point of the protractor on A. Align the mark labeled 0 with the ray.
3) Locate and draw point C at the mark labeled 135. Draw AC.
A B
Angle MeasureAngle Measure
Use a protractor to draw an angle having a measure of 135.
1) Draw AB
2) Place the center point of the protractor on A. Align the mark labeled 0 with the ray.
3) Locate and draw point C at the mark labeled 135. Draw AC.
C
A B
Angle MeasureAngle Measure
Once the measure of an angle is known, the angle can be classified as oneof three types of angles. These types are defined in relation to a right angle.
Angle MeasureAngle Measure
Once the measure of an angle is known, the angle can be classified as oneof three types of angles. These types are defined in relation to a right angle.
Types of Angles
A
Angle MeasureAngle Measure
Once the measure of an angle is known, the angle can be classified as oneof three types of angles. These types are defined in relation to a right angle.
Types of Angles
obtuse angle 90 < m A < 180
A
Angle MeasureAngle Measure
Once the measure of an angle is known, the angle can be classified as oneof three types of angles. These types are defined in relation to a right angle.
Types of Angles
A
obtuse angle 90 < m A < 180
A
Angle MeasureAngle Measure
Once the measure of an angle is known, the angle can be classified as oneof three types of angles. These types are defined in relation to a right angle.
Types of Angles
A
right angle m A = 90
obtuse angle 90 < m A < 180
A
Angle MeasureAngle Measure
Once the measure of an angle is known, the angle can be classified as oneof three types of angles. These types are defined in relation to a right angle.
Types of Angles
A
right angle m A = 90
A
obtuse angle 90 < m A < 180
A
Angle MeasureAngle Measure
Once the measure of an angle is known, the angle can be classified as oneof three types of angles. These types are defined in relation to a right angle.
Types of Angles
A
right angle m A = 90
acute angle 0 < m A < 90
A
obtuse angle 90 < m A < 180
A
Angle MeasureAngle Measure
Classify each angle as acute, obtuse, or right.
110°
90°40°
50°
130° 75°
Angle MeasureAngle Measure
Classify each angle as acute, obtuse, or right.
110°
90°40°
50°
130° 75°
Obtuse
Obtuse
Acute
Acute Acute
Right
Angle MeasureAngle Measure
5x - 7
B
The measure of B is 138.Solve for x.
Angle MeasureAngle Measure
5x - 7
B
The measure of B is 138.Solve for x.
B = 5x – 7 and B = 138
Given: (What do you know?)
Angle MeasureAngle Measure
5x - 7
B
The measure of B is 138.Solve for x.
B = 5x – 7 and B = 138
Given: (What do you know?)
5x – 7 = 138
5x = 145
x = 29
Angle MeasureAngle Measure
5x - 7
B
The measure of B is 138.Solve for x.
B = 5x – 7 and B = 138
Given: (What do you know?)
5x – 7 = 138
5x = 145
x = 295(29) -7 = ?
145 -7 = ?
138 = 138
Check!
Angle MeasureAngle Measure
9y + 4H
The measure of H is 67.Solve for y.
Angle MeasureAngle Measure
9y + 4H
The measure of H is 67.Solve for y.
H = 9y + 4 and H = 67
Given: (What do you know?)
Angle MeasureAngle Measure
9y + 4H
The measure of H is 67.Solve for y.
H = 9y + 4 and H = 67
Given: (What do you know?)
9y + 4 = 67
9y = 63
y = 7
Angle MeasureAngle Measure
9y + 4H
The measure of H is 67.Solve for y.
H = 9y + 4 and H = 67
Given: (What do you know?)
9y + 4 = 67
9y = 63
y = 79(7) + 4 = ?
63 + 4 = ?
67 = 67
Check!
Angle MeasureAngle Measure
Angle MeasureAngle Measure
