I can use theorems, postulates and/or definitions to prove theorems about triangles including: measures of interior angles of a triangle sum to 180 degrees.

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Presentation transcript:

I can use theorems, postulates and/or definitions to prove theorems about triangles including: measures of interior angles of a triangle sum to 180 degrees

The sum of the measures of the angles of a triangle is 180 degrees

Let’s prove it. First Draw this picture, then write the proof below

If I know two of the angles in a triangle, to find the third angle I…. CAN SET THE SUM OF THE THREE ANGLES EQUAL TO 180 AND SOLVE FOR THE THIRD ANGLE

This is just an example…NOT the example from your notes…..

The measures of each exterior angle of a triangle equals the sum of it’s two remote (non- adjacent) interior angles.

Let’s prove it. First draw this picture, then write the proof.