In this lesson we used protractors to measure the three angles outside of various triangles by extending their sides. We added up our results and conjectured that the sum of the exterior angles of a triangle is 360 degrees. We also compared the measure of each exterior angle to the sum of its opposite exterior angles and conjectured that these measures are equal.
We created our next triangle theorems:
Triangle Theorem 2: The sum of the exterior angles of a triangle is 360 degrees.
Triangle Theorem 3: The measure of an exterior angle in a triangle is equal to the sum of the opposite interior angles.
For Extra Practice and Explanation: http://www.regentsprep.org/Regents/math/geometry/GP5/LExtAng.htm
For a Video Explanation: http://www.youtube.com/results?search_query=khan+academy+exterior+angles
Attached below are the classwork and homework assignments for Topic 2.