Bellwork

1
Bellwork
Clickers

• Solve for x
• 3x52x-436

2
Bellwork Solution

• Solve for x

3
Bellwork Solution

• Solve for x

4
Bellwork Solution

• Solve for x

5
Measure and Classify Angles

• Section 1.4

6
The Concept

• Today were going to discuss the different kinds
  of angles
• Were also going to talk about adding and
  bisecting angles

7
Definition

• Angle
• Object that is created by the connection of two
  rays at the same endpoints
• Consists of two sides and a vertex
• Named by three points (of which one is the
  vertex) or just by the vertex if it is not shared
  with another angle

Object that is created by the connection of two
rays at the same endpoints Consists of two sides
and a vertex Named by three points (of which one
is the vertex)
B
Angle
1.4
A
C
Indicates angle
Axis of symmetry
Vertex
8
Congruence

• Similar to our look at line segments, we have to
  be aware of the difference in use of the
  congruence and equals signs

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Protractor Postulate

• The measure of an angle (denoted m) is equal to
  the absolute value of the difference between the
  real numbers for the two rays as they cross a
  protractor
• In other words, if you measure an angle with a
  protractor we can be reasonably certain that its
  correct

10
Classification
B

• There are four kinds of angles
• Acute
• Measuring less than 90 degrees
• Right
• Measuring 90 degrees
• Obtuse
• Measuring larger than 90 degrees
  and less than 180
• Straight
• Measuring 180 degrees

A
C
B
A
C
B
A
C
A
B
C
11
On your own

• What kind of angle is shown below?

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On your own

• What kind of angle is shown below?

13
On your own

• What kind of angle is shown below?

14
Angle Addition Postulate

• If P is in the interior of ?RST, then the measure
  of ?RST is equal to the sum of the measures of
  ?RSP and ?PST.

R
P
S
T
15
Example
R
P
35
S
23
T
58o
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On your own

• What is the measure of angle ABD, if the measure
  of angle ABC is 102o?

B
35o
C
A
D
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Application

• Find if is 72 degrees

R
P
3x6
S
2x-9
T
18
Congruency

• Two angles that have the same measure are
  considered congruent
• Example 4

19
Homework

• 1.4
• 2-38 even, 51-58 (dont measure, just classify)

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Bisector angles

• Similar to bisectors of lines, a bisector of an
  angle is a ray that shares the end point of a
  given angle that splits the measure of the angle
  in half

R
P
S
T
21
Application

• Find if is 32o and SP
  is a bisector

R
P
S
T
22
Most Important Points

• Definition of angles
• Classification of angles
• Angle addition postulate
• Congruent Angles
• Bisector angles