Unit 2, Lesson 13# Angle Sum of a Triangle

EngageNY 45 min(s)

Students know the angle sum theorem for triangles; the sum of the interior angles of a triangle is always 180°. Students present informal arguments to draw conclusions about the angle sum of a triangle. It does not matter what kind of triangle it is (i.e., acute, obtuse, right); when the measure of the three angles are added, the sum is always 180°.