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May 1 – (- 625 ), 2011
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7th Grade Math Class work #173
Aim: SWBAT determine the sum of the angles of any given polygon.
Please Do Now 
1) Solve for n in the equation an – bc = d
2) At Best Buy, they’re offering CD’s in bundles. A bundle of 200 CD’s costs $56. At Circuit City,
they’re having a sale on 150 CD’s for 52.50. Which place has the better deal? Explain why.
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3) Write the equation that the table below represent.
x
y
1
14
2
22
3
30
Answer: _____________________________
Finished Early?
 How many degrees are in any given quadrilateral? __________________________________________

How do you know?
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We are KIPP: STAR and we are a Team and a Family.
FACT/ TOPIC
DETAILS
TRIANGLE
The sum of the angles of any triangle is _____________________.
QUADRILATERAL
The sum of the angles of any quadrilateral is _________________
because we can create two triangles from every quadrilateral.
PENTAGON
What would be the total sum of the angles of a pentagon?
Step 1: Draw the shape.
Step 2: From one ____________ (or point), draw diagonals to as
many of the other points.
Step 3: Count the number of triangles and multiply by 180.
The sum of the angles of any pentagon is ____________________
Shape
# of Sides
# of Triangles
Total Degrees
Triangle
Quadrilateral
Pentagon
We are KIPP: STAR and we are a Team and a Family.
Let’s Practice 
Show your work. When you are done with the first section, choose your preference of math problems (mild, hot
or spicy). If you get done early, try to complete the other two.
1. Find the sum of the angles of a hexagon.
The sum of the angles of any hexagon is ____________________
2. Find the sum of the angles of a heptagon.
The sum of the angles of any hexagon is ____________________
MILD
3. Fill in the chart and make a prediction as to what would be the sum of the angles of an octagon and a
nonagon (a nine-sided polygon ).
Shape
# of Sides
# of Triangles
Total Degrees
Triangle
Quadrilateral
Pentagon
Hexagon
Heptagon
Octagon
Nonagon
We are KIPP: STAR and we are a Team and a Family.
HOT
4. A decagon contains the following angles:
140, 140, 115, 115, 120, 120, 155, 155
If the last two angles are of the same value, what is the measure of that
angle?
Answer: ____________________________
SPICY
5. A dodecagon has 12 sides. What is the sum of all of its angles?
Answer: ____________________________
6. Complete the chart. Lofl to KIPPsters who can write an expression based off of this chart. 
Shape
# of Sides
# of Triangles
Total Degrees
Hexagon
Heptagon
Octagon
Nonagon
Decagon
Write an expression on how to find the degrees by knowing the number of sides, s:
__________________
We are KIPP: STAR and we are a Team and a Family.
_________________________________________
May 1 – (- 625 ), 2011
_________________________________________
____________________________________
7th Grade Math Homework #173
Show your work. When you are done with the first section, choose your preference of math problems (mild, hot
or spicy). If you get done early, try to complete the other two.
1. Find the sum of the angles of a nonagon.
The sum of the angles of any nonagon is ____________________
2. Find the sum of the angles of an octagon.
The sum of the angles of any octagon is ____________________
MILD
3. Fill in the chart and make a prediction as to what would be the sum of the angles of an octagon and a
nonagon (a nine-sided polygon ).
Shape
# of Sides
# of Triangles
Total Degrees
Pentagon
Hexagon
Heptagon
We are KIPP: STAR and we are a Team and a Family.
[insert any questions from the test data that we need to spiral]
We are KIPP: STAR and we are a Team and a Family.