Do Now Solve for x and y 3-31-09 15 5 30 x y A B D C E

Objective We will continue to look at the side splitter theorems.

We will continue to look at the side splitter theorems.

Homework Page 311 #1-5 6 16 8 12 1/4

Page 311 #1-5

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16

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Theorems! Make sure you have the theorems in your notes!

Make sure you have the theorems in your notes!

Theorem 4.1 The Parallel Side Splitter Theorem If the segment with endpoints on the two sides of a triangle is parallel to the third side then… The segment splits the sides it intersects proportionally The ratio of the length of the side of the triangle to the length of the parallel segment is the common ratio

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

The segment splits the sides it intersects proportionally

The ratio of the length of the side of the triangle to the length of the parallel segment is the common ratio

Theorem 4.2 The Proportional Side-Splitter Theorem If the segment with endpoints on two sides of a triangle splits those sides proportionally then the segment is parallel to the third side.

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

Using Theorem 4.2 Is ? BC = ? 20 10 4 2 6 A B D C E

Is ?

BC = ?

Using Theorem 4.2 15 10 40 5 Is ? DE = ? 20 A B D C E

Is ?

DE = ?