Transcript Proportion and Reasoning

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Take out your 11.1 Worksheet ready to be
stamped.
Take out a compass and protractor.
What does it mean for polygons to be similar?
Give a counterexample to each statement.
(Can be in the form of a picture or
explanation.)
◦ Two polygons that have corresponding angles
congruent must be similar.
◦ Two polygons that have corresponding sides
proportional must be similar.
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11.2 WS is due Wednesday
Parts 1-2 of the house project are due
Wednesday
Bring your raffle tickets for an auction on
Wednesday
Bring your compasses every day next week
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Discover shortcut methods for determining
similar triangles
Use proportions to find measures in similar
figures
Use problem solving skills
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We concluded that you must know about both
the angles and the sides of two polygons in
order to make a valid conclusion about their
similarity.
However, triangles are unique. Remember
there were 4 shortcuts for triangle
congruence: SSS, SAS, ASA, and SAA.
Are there shortcuts for similarity also?
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Suppose two triangles had one corresponding
angle congruent. Would the triangles be
similar?
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From the second step in the investigation you
see there is no need to check AAA, ASA, or
SAA similarity conjectures.
Because of the Triangle Sum Conjecture and
the Third Angle Conjecture AA Similarity
Conjecture is all you need.
So SSS, AAA, ASA and
SAA are shortcuts for
triangle similarity.
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Discover shortcut methods for determining
similar triangles
Use proportions to find measures in similar
figures
Use problem solving skills
1. Find the missing values.
Show your work and
Explain your reasoning
2. Write the similarity statement and give a
proof of why the triangles are similar.
1. Find the missing values.
Show your work and
Explain your reasoning
2. Write the similarity statement and give a
proof of why the triangles are similar.