Download Segment Addition Postulate

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DO NOW 9/15:
In the problem below, AB = 9 and
AC = 14. Describe and correct
the error made.
Segment Addition
Postulate
Agenda
1.
HW Review (10 min)
2.
Segment Addition Jigsaw (25 min)
3.
Congruent Segments/Midpoint (10 min)
4.
Debrief (10 min)
+ HW Review
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Segment Addition Jigsaw

Each person starts with a sheet with segment addition problems on it.
There will be a timer for each round.
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Round 1: Draw a diagram for each problem (2 min)
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Round 2: Write an equation for each problem (8 min)
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Round 3: Subtitute numbers into equation for each problem (5 min)
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Round 3: Solve each problem (and CHECK YOUR ANSWER!!) (10 min)
**Between each round, make sure the person before you was correct!**
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Congruent Segments
and Midpoints

**MUST BE IN NOTES!**
Congruent – two figures that are the same size and shape
Shown on
diagrams
as“tic marks”

Midpoint – the point that divides the segment into two
congruent segments.
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Midpoint of a Segment: Practice
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Debrief

How are congruent segments related to midpoints?

Why is it important to follow each step (diagram, equation,
substitution, solution) when using segment addition?
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DO NOW 9/16:
If M is the midpoint of LN, then
what is the length of LM?
x + 6 cm
L
5x – 2 cm
M
N
Naming Angles /
Angle Pairs
Agenda
1.
Naming Angles (10 min)
2.
Vertical Angles/Adjacent Angles (5 min)
3.
Supplementary/Complementary Angles (5 min)
4.
Angle Addition Postulate (15 min)
5.
Debrief (10 min)
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Pool/Snooker Angles
2014 World Champ Video - $1.9 million prize

What angles are involved in the game?
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Naming Angles

We name angles with three
points (capital letters).

The middle letter is always the
vertex.

Sometimes textbooks and tests
will label an angle with a
number on the interior of the
angle.
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If there is only one angle, we
can name that angle using
ONLY the vertex. However, if
there are more than one angle,
we need to use all 3 points.
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Supplementary and
Complementary Angles
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Complementary Angles – two
angles that add up to 90°
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Supplementary Angles – two
angles that add up to 180°
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Other Angle Pairs
**MUST BE IN NOTES!**

Vertical Angles – any pair of angles that
share a vertex but don’t share any sides
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Adjacent Angles – any pair of angles that
share a vertex and share one side
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Linear Pair – a specfic type of adjacent
angles that are supplementary
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Angle Addition Postulate
**MUST BE IN NOTES!**
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If Z is a point in the interior of ∠ABC, then m∠ABZ + m∠ZBC =
m∠ABC.
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Debrief
(EXIT TICKET)

Can two obtuse angles be supplementary? Why or why not?
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Exit Ticket: Angle Addition Worksheet
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DO NOW 9/17:
In the diagram below, name:
1. an acute angle
2. an obtuse angle
3. a vertical pair
4. a linear pair
5. a complementary pair
Segment and Angle
Addition Postulate
Agenda
1.
Angle Bisectors (10 min)
2.
Angle Addition with Angle Bisectors (10 min)
3.
Clock Angles (10 min)
4.
Debrief (10 min)
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HW Review
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Angle Bisector
**MUST BE IN NOTES!**

Angle bisector – a ray that divides an angle into two
congruent angles.
∠CAB ≅ ∠BAD
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4-Corner Drill
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In teams, solve the problem on the board. When you have an
answer, head to the corner with the correct answer choice.

1 point – First team at correct answer
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1 point – Ending up at correct answer
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1 point – Explaining answer correctly
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Segment Addition
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Segment Addition with Midpoint
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Angle Addition
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Angle Addition with Bisectors
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Debrief

What helped speed things up in your group? What slowed
things down? How can you utilize strategies from today to
help you on your quiz tomorrow?
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DO NOW 9/18
Angle and Segment Addition Quiz!
Angle Bisectors
Agenda
1.
Angle and Segment Addition Quiz (20 min)
2.
Clock Angle Bisectors (20 min)
3.
Debrief (10 min)
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DO NOW 9/19:
Find the value of x and the m∠DEC
Angles on Parallel Lines
Agenda
1.
Note Check!
2.
Clock Video (5 min)
3.
Clock Angles Activity (20 min)
4.
Formula Creation (10 min)
5.
Debrief (10 min)
+ There’s No Time Like Math Time!
“How many times is the second hand exactly
between the minute and hour hand?”

Watch this until you go crazy.

Then watch this.
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Then use this.
Is this an angle bisector?
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What information will we need to
figure this out?
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…Maybe this will help?
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t = # of seconds (since 12:00:00 or zero degrees)
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S = 6t
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M = t/10
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H = t/120
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Measure between the two hands has to be equal, and add up to 360°
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M – S = S – H + 360
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Debrief

What previous math skills did you draw on to solve this
problem?
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Extension (Classwork Extra Credit):
1.
How many times a day are all 3 hands aligned?
2.
What are 3 times when the Hour hand is directly between
the second and minute hand?
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HW This Weekend

Come up with a statement that fits the following structure:
“ If _________________, then ___________________.”
...and DOESN’T seem logical!
Ex. “If there is a forest fire, then fish will die.”