What Happened Yesterday? Let’s Review! Line Ray Line Segment Angle Vertex Point Triangles ...
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Transcript of What Happened Yesterday? Let’s Review! Line Ray Line Segment Angle Vertex Point Triangles ...
What Happened Yesterday?
• Let’s Review! Line Ray Line Segment Angle Vertex Point Triangles Intersection
1.2 Measurement of Segments and Angles
Measuring segments:
Ruler or meter stick units of measure
Match item being measured with proper unitU.S.: Inches, feet, yards, miles etc.Metric: km, cm, m, mm
Distance: absolute value
m AB1 2 3 4
A B
|2-3| or |3-2|
= |-1| = |1|
= 1 = 1
The length of AB = 1 cm
cm
Measuring angles:
Unit of measure:
Degrees
Tool: protractor
Angle measurement
Angle measurement is the opening from one ray to the next ray.
We usually use the inside measurement, 180 degrees or less.A full turn is a circle and measures 360 degrees.
P
A R
m<PAR = 90m<A = 90
Angle measurement
m<1 = 1351
Let’s think about the measure of the angle formed by the hands of a clock at 3:00 and 4:30
Classify angles by size
Acute: 0<90
Right: 90
Obtuse: 90<180
Straight: 180
Parts of a degree:
1 Degree = 60’ (minutes)1 Minute = 60” (seconds)So, 87 = 8730’
1
2
90 = 8959’60”
Find m<CBD
A
B
C
D
m<ABD = 90
m<ABC = 7421’10”
90
- 7421’ 10”
1538’50”
Congruent angles and segments
Symbol: =
= < have the same measure
= have the same length
<A = <B
A 60 B 60
Congruency
Tick marks show congruencyA
C
B
X
Z Y
Can you name congruent angles and segments?
Example
AB
C
1
2
m<ABC = 90
m<1 = (3x+4)
m<2 = (x+6)Find both angles!3x + 4 + x + 6 = 90 so m < 1 = 64
4x + 10 = 90 m < 2 = 26
4x = 80
X = 20
Recap!
Acute AngleCongruent AngleCongruent SegmentsDegreeObtuse AngleRight Angle
YOUR TURN
Work with a partner
Pg 14 #1,2, 5-8, 10, 12, 13-16, 18