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1.4 A Notes.notebook September 10, 2014
Welcome to Class!!!Please GET:~Stick Quiz~Protractor
~Whiteboard/Pen
• ray• opposite rays• angle• side• vertex
Todays Vocabulary• degree• right angle• acute angle• obtuse angle• congruent angles• angle bisector
Questions On Homework?
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1.4 A Notes.notebook September 10, 2014
1.4 A Notes.notebook September 10, 2014
I can ... write precise definitions of basic geometric terms.I can... draw, measure and interpret geometric diagrams using given information.I can... appropriately mark shapes with geometric notation.
A Ray begins at a point and extends infinitely in ...
1.4 A Notes.notebook September 10, 2014
Rays are named with endpoint FIRST and another point on the line.
Ex:
Opposite Rays: If you pick one point on a line, two rays extend from it in opposite directions! Opposite rays are collinear. Ex:
angle:two noncollinear rays that have a common endpoint.
vertex: the common endpoint of the two rays that form an angle
A
B
C
sides: the rays that form the angle
Naming an angle:
3
1.4 A Notes.notebook September 10, 2014
Name as many angles as possible!
A. Name all angles that have B as a vertex.
1.4 A Notes.notebook September 10, 2014
B. Name the sides of ∠5.
1.4 A Notes.notebook September 10, 2014
degrees: the measurement of an angle This comes from dividing a circle into 360 parts,
0o
Protractors measure from zero in both directions! Always be careful you are reading the correct measurement!
.
How to measure an angle using a protractor:Step 1: Place the center mark of the protractor on the vertexStep 2: Line up the 0mark with one side of the angleStep 3: Read the measure on the protractor scaleStep 4: Be sure to read the scale that has the 0mark you are using!
A
B
C D E
F
1.4 A Notes.notebook September 10, 2014
right angle: an angle that measures 90 degrees or is marked with a square, or marked with 90 degrees.
Examples Nonexamples
90
If it is not marked, then you need to assume it is not 90. Or measure with protractor!
acute angle: an angle that measures less than 90 degrees
Examples Nonexamples
1.4 A Notes.notebook September 10, 2014
obtuse angle: an angle that measures more than 90 degrees but less than 180 degrees
Examples Nonexamples
straight angle: an angle that measures 180 degrees
1.4 A Notes.notebook September 10, 2014
1. Name each angle with proper notation.2. Classify as right, acute, or obtuse.3. Use a protractor to measure each angle to the nearest degree.4. Paste this into your notes.
congruent angles: two angles that have the same measurement
angle bisector: a ray that contains the vertex and divides the angle into two congruent angles
C
A
T
D
O
G
D E
F
G
Markings!
Markings!
1.4 A Notes.notebook September 10, 2014
Find m∠BHC and m∠DJE if ∠BHC ≅ ∠DJE, m∠BHC = 4x + 5, and m∠DJE = 3x + 30.
Answer: m∠BHC = 105, m∠DJE = 105
1.4 A Notes.notebook September 10, 2014
Measure and Classify AnglesIn the figure, ∠ABD ≅ ∠FHG. If m∠ABD = 3x + 6 andm∠FHG = x + 26, find the measures of ∠ABD and ∠FHG.
The measures of ∠ABD and ∠FHG are 36.
You can check you solution by substituting 10 for x in the expression for ∠FHG.
Answer
1.4 p.41 #1329o, 3035, 3741o, 5052
Homework Different from sheet!!!