4'2 Angles of Triangles

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4.2 Angles of Triangles
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Theorems

• Angle Sum Thm sum of angles of triangle is 180
• 3rd Angle Thm If 2 angles in 2 triangles are
  congruent, then 3rd angles are congruent, too.

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Exterior Angles

• Exterior Angle
• Exterior Angle Thm meas of ext angle sum of 2
  remote int angles

2
1
3
4
Find the meas of each numbered angle in the
figure
1
119?
7
75?
2
8
6
82?
62?
5
9
3
4
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Corollaries

• Corollary (cor) statement that can be easily
  proved with a thm (like a mini-thm)
• Cor 4.1 acute angles of rt triangle are comp
• Cor 4.2 there can be at most 1 rt or 1 obtuse
  angle in a triangle

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• 4.2 p. 189
• (12-38 even, 56-64 all)