Ch 7'5 Proportions and Similar Triangles

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Ch 7.5 Proportions and Similar Triangles

• Use the Triangle Proportionality Theorem and its
  Converse

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Theorem 7.4

• Triangle Proportionality Theorem
• Words If a line parallel to one side of a
  triangle intersects the other two sides, then it
  divides the two sides proportionally.
• Symbols In ?QRS, if TU ? QS, then
  .

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Find the segment lengths

• Find the value of x

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Theorem 7.5

• Converse of the Triangle Proportionality Theorem
• Words If a line divides two sides of a triangle
  proportionally, then it is parallel to the third
  side.
• Symbols In ?QRS, if , then TU ?
  QS.

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Determine Parallel lines

• Is QR parallel to ST? Why?

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• A midsegment of a triangle is a segment that
  connects the midpoints to two sides of a
  triangle.
• Theorem 7.6
• The Midsegment Theorem
• Words The segment connecting the midpoints of
  two sides of a triangle is parallel to the third
  side and is half as long.
• Symbols In ?ABC, if CD DA, and CE EB, then
  DE ? AB and DE (1/2)AB.

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Find the value of the variable
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Classwork

• Geometry book
• Page 390
• 1-10
• Neighbor help is ok