Triangle Application Theorems

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Triangle Application Theorems

• Lesson 7.1

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• Theorem 50- The sum of the measures of the angles
  of a triangle is 180º.

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• Exterior angles of a polygon
• Definition- an exterior angle of a polygon is an
  angle that is adjacent to and supplementary to an
  interior angle of the polygon.

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• More Theorems!
• Theorem 51- The measure of an exterior angle of a
  triangle is equal to the sum of the measures of
  the remote interior angles.
• Theorem 52- A segment joining the midpoints of
  two sides of a triangle is parallel to the third
  side and its length is 1/2 the length of the
  third side. (Midline Theorem)

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• Proof of Theorem 51-
• mltBCA mlt1 180
• mltBCA m ltB mltA 180
• m ltBCA m lt1 m ltBCA m ltB m ltA
• m lt1 m ltB m ltA

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