 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.

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Presentation transcript:

 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.

 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

 Discover shortcut methods for determining similar triangles  Use proportions to find measures in similar figures  Use problem solving skills

 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?

 Suppose two triangles had one corresponding angle congruent. Would the triangles be similar?

Is AA a Similarity Shortcut?

 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.

Is SSS a Similarity Shortcut?

So SSS, AAA, ASA and SAA are shortcuts for triangle similarity.

Is SAS a Similarity Shortcut?

 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.