Chapter 2
Points, Lines, and Angles
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Goal
Tell type of angle. Label angles. Measure angles.
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Check
a ) ray b) line segment c) line
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angle a figure formed by the
intersection of two rays
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angle
Rays are called sides.
Point where sides intersect is called a vertex.
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angle examples non-examples
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Naming angles
Method 1 angle x angle y
Method 2 angle ABC angle CBA
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List everything you can tell about this angle.
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-Angle – 2 rays that intersect
-Sides – rays
- Point where rays intersect – vertex
- Angle ABC or CBA
-Measured in degrees
- 60 degrees
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Types of Angles
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Right Angle
Right angle an angle whose measure is 90 degrees
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right angles not right angles
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Acute angle acute angle
• an angle• whose measure • is less than 90
degrees
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acute angles not acute angles
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obtuse angle
obtuse angle• an angle • whose measure is • greater than 90
degrees but• less than 180 degrees
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Obtuse angle
Why are these obtuse angles?
Obtuse Angles Not Obtuse
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What type of angle? Why?
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Why type of angle? A? B? C? D? E? F?
a.acute
b.right angle
c.obtuse
d.acute
e.right angle
f. obtuse
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straight angle
straight angle an angle whose measure is 180 degrees
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straight angles not straight angles
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Page 28 number 1 - 10
1. measure of angle ARF
180 degrees
straight angle
2. measure of angle CRF
120 degrees
obtuse
3. measure of angle BRF
155 degrees obtuse 30
adjacent angles
adjacent angle two angles have same vertex share one ray
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List adjacent angles
Adjacent angles
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List adjacent angles
Adjacent angles
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adjacent angles not adjacent angles
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Page 29 1.Angle CDB is adjacent to angle _____
2. Angle TUV is adjacent to angle ____
3. Angle SRP is adjacent to angle ____
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vertical angles
Vertical angles When two lines
intersect two pairs of
vertical angles are formed
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vertical angles
Vertical angles are NOT adjacent.
Vertical angles have the same measure.
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Which angles are vertical?
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Which angles are adjacent?
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Page 30
Vertical angles
1. angle YPV and angle ____
1. angle YPV and angle RPS
2. angle QPR and angle _____
3. angle QPR and angle VPT
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complementary angles two angles sum of measures is 90 degrees
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complementary angles
What angles are complementary?
Why?
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complementary angles
Are these angles complementary?
Why or Why not?
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complementary angles
not complementary angles
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Supplementary angles two angles sum of measures is 180 degrees
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Supplementary angles two angles sum of measures is 180 degrees
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Why are figure 1 and figure 2 both examples of supplementary angles?
supplementary angles
not supplementary angles
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Review of Angles
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