The students will investigate the sum of the interior angles of various triangles and conjecture and prove the following theorem: • The sum of the interior angles in a triangle is 180° . The extension activities include conjecturing and proving the following theorems: The sum of the interior angles in a quadrilateral is 360° . The sum of the measures of the interior angles in a convex n-gon is 180°(n-2).
Gambino, Renee, "Exploring Angles" (2006). Lesson Plans. 43.
Geometer’s Sketch pad