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Reteaching: Triangle Angle Sum Theorem

Part 1: Exploration

Interact with the app below for a few minutes.   Be sure to change the locations of this triangle's vertices each time before you drag the slider!

After interacting with the app above, what do you notice?

Part 2: Lesson

Triangle sum theorem: The sum of the interior angle measures of a triangle is 180 degrees.
Let's talk about the following problem together.
  • Find the measure of angle C.
  • Check your answer by seeing if the 3 angles measures add up to 180 degrees.
Let's try the following problem together.
  • Find the value of x.
  • Check your answer by seeing if the 3 angles measures add up to 180 degrees.

Part 3: Independent Practice

Try the following problem by yourself.
  • Find the value of x.
  • Check your answer by seeing if the 3 angles measures add up to 180 degrees.