# HSG-CO.C.10

Prove theorems about triangles. Theorems include: measures of interior angles of a triangle sum to $180^\circ$; base angles of isosceles triangles are congruent; the segment joining midpoints of two sides of a triangle is parallel to the third side and half the length; the medians of a triangle meet at a point.

## Tasks

Seven Circles I

Classifying Triangles

Finding the Area of an Equilateral Triangle

Midpoints of Triangle Sides

Congruent angles in isosceles triangles

Sum of angles in a triangle