Do NowDo NowMake sure you have the followingMake sure you have the following

Lined paperLined paperRulerRuler

Partner with a bookPartner with a book

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If you were told the ratio from figure A to B was 150% and the side length of A was 2 inches. How long is the side

length of figure B.

ObjectiveObjective

Look at the side splitter theorems. Look at the side splitter theorems.

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Experiment timeExperiment time

You and a partner will have 15 minutes to You and a partner will have 15 minutes to work on the experiment on page 308.work on the experiment on page 308.

You should each complete Part 1A of the You should each complete Part 1A of the experiment in your notebook. Use lined experiment in your notebook. Use lined paper to make the parallel lines and paper to make the parallel lines and measure the distances between lines and measure the distances between lines and the point. the point.

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Take a minute to organize your Take a minute to organize your conclusions. conclusions.

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Label one of your from #1 Label one of your from #1 triangles like this. triangles like this.

Measure AB and AD. What do you find?Measure AB and AD. What do you find?Measure AE and AC. What do you find?Measure AE and AC. What do you find?

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A

B C

D E

ConclusionsConclusions3-30-09

Theorem 4.1Theorem 4.1The Parallel Side Splitter TheoremThe Parallel Side Splitter Theorem

If the segment with endpoints on the two sides of a If the segment with endpoints on the two sides of a triangle is parallel to the third side then…triangle is parallel to the third side then…

The segment splits the sides it intersects The segment splits the sides it intersects proportionallyproportionally

The ratio of the length of the side of the triangle The ratio of the length of the side of the triangle to the length of the parallel segment is the to the length of the parallel segment is the common ratiocommon ratio AB AC BC

AD AE DE= =

Theorem 4.2Theorem 4.2The Proportional Side-Splitter TheoremThe Proportional Side-Splitter Theorem

If the segment with endpoints on two sides If the segment with endpoints on two sides of a triangle splits those sides of a triangle splits those sides proportionally then the segment is parallel proportionally then the segment is parallel to the third side.to the third side.

||AB AC

BC DEAD AE

= →

H/WH/W

Pg 311 #1-5Pg 311 #1-5

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