Triangle Angle-Sum Theorem

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1. Use the slider to make the angles of the triangle lie on the straight line. Make a conjecture about the sum of the angles in a triangle.
2. Use points A, B, and C to change the triangle. Now use the slider again to make the angles of the triangle lie on the straight line. Is your conjecture from question #1 always true?

Barbara Perez, 10/30/06, Created with GeoGebra