Triangle Angle Sum & Exterior Angle Theorems

Jill Casey, Jun 28, 2017


  • 1. Triangle Angle Theorems
  • 2. Exterior Angle Theorem

1.

Triangle Angle Theorems

[color=#000000]Interact with the applet below for a few minutes.  [br]Then, answer the questions that follow.  [br][br][/color][i][color=#980000]Be sure to change the locations of the triangle's WHITE VERTICES each time before you drag the slider!!! [/color][/i]
Triangle Angle Sum Theorem
From your observations, what is the sum of the measures of the interior angles of [i]any triangle?  [/i]
Sum of the Exterior angles of a triangle
[color=#000000]From your observations, what is the sum of the measures of the exterior angles of [i]any triangle?  [/i][/color]
– Jill Casey, Tim Brzezinski

2.

Exterior Angle Theorem

Exterior Angle Theorem
Exterior Angle Theorem
The two colored angles are said to be the "remote interior" angles from the labeled exterior angle. What do you think the definition of [u]remote interior angle[/u] is?
Exterior Angle Theorem #2
When you moved the slider, the two remote interior angles moved. What did you notice that happened? What do you think the [u]Exterior Angle Theorem[/u] is?
– Tim Brzezinski, Jill Casey

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