STANDARD G.CO.C.10
GEO

Prove and apply theorems about triangles.
• Include multi-step proofs and algebraic problems built upon these concepts.
• Examples of theorems include but are not limited to:
   o Angle Relationships:
      • The sum of the interior angles of a triangle is 180 degrees.
      • The measure of an exterior angle of a triangle is equal to the sum of the two non-adjacent interior angles of the triangle.
   o Side Relationships:
      • The length of one side of a triangle is less than the sum of the lengths of the other two sides.
      • In a triangle, the segment joining the midpoints of any two sides will be parallel to the third side and half its length.
   o Isosceles Triangles:
      • Base angles of an isosceles triangle are congruent.