Ch 5.1 Exterior Angle Theorem
- David Greenstein
Construction of the Exterior Angle Theorem
1. Construct a line through side AC of the triangle. 2. Construct a line through the vertex B that is parallel to side AC. 3. Measure the exterior angle at C and all three interior angles. 4. Observe the exterior angle measure and the sum of the remote interior angles. Move ABC and observe what happens to the angle measures.