n 1' Solve the equation: n 23 56'

1
Bell Ringers

• n 1. Solve the equation n 23 56.
• Explain the process that you used to solve
  the equation. 
• Classify each figure as a quadrilateral or
  non-quadrilateral
• 3. Rename the following fractions in lowest
  terms.     
• a.  10/12  b.  15/20  c.  3/18  d.  3/7

n 33 I subtracted 23 from 56 to determine n.
quadrilateral!
non
non
non
5/6 3/4 1/6 3/7
2
One More Bell Ringer!
Amanda has 100 coins in her coin collection. 10
coins are from Africa. 20 coins are from
Europe. 15 coins are from Asia. 5 coins are from
Australia. 20 coins are from South America. The
rest of the coins are from North America. What
percentage of the coins are from North America?
30
3
Objective 28
Know that the sum of the interior angles of a
triangle is 180 degrees and find the missing
angle when given two angles of a triangle.
4
180 Degrees!

• Draw a triangle with a straight edge.
• Use your protractor to determine the measure of
  each angle in your
• triangle.
• Find the sum of the angles and write the sum in
  your triangle.
• Check with your partner to see how your sums
  compare.
• If youre waiting try another triangle.

5
180 Degrees!
You can use the properties of a triangle to
determine the measure of an angle without using a
protractor! The sum of the interior angles of a
triangle is always 180 degrees. When given two
angles you can determine the third angle with
an algebraic equation a b c
180º
EXAMPLE Determine angle c. a 55 º b 90 º c
x
a
55 º 90 º x 180 º 145 º x 180 º 180 º
145 º x x 35º
b
c
6
Name that angle!
n
2.
1.
60º
35º
90º
n 55º
x
60º
x 60º
Can you name that triangle too?
4.
z
Classify each triangle by its angles and sides.
3.
a

• acute equilateral
• right scalene
• obtuse scalene
• acute isosceles

25º
70º
70º
60º
z 40º
a 95º
7
Closure
Create a triangle. Measure the angles and sides.
Classify your triangle. Write down your data on
a separate sheet of paper. We arent always
exact with a protractor. Be sure your angles
add up to 180º! Give your triangle to your
partner to measure and classify. Try to measure
and classify your partners triangle. See if you
have a match!
HWSkills Quiz
8
More Practice
For more practice with polygons triangles,
click on the links below. http//www.321know.com/
geo612x5.htmsection2 http//argyll.epsb.ca/jreed
/math9/strand3/triangle_angle_sum.htm http//www.
aaamath.com/geo612-find-3rd-angle-triangle.html h
ttp//nlvm.usu.edu/en/nav/frames_asid_165_g_2_t_3.
html?openinstructions http//www.studystack.com/
hangman-13166