One Hundred and Eighty

Use the applet below to create a triangle

  • Use the Text tool to label the 3 interior angles as  and .
  • Mark the midpoints of 2 of the sides.
  • Extend the side of the triangle without the midpoint in both directions to make a line.
  • Use what you know about rotations to create a line parallel to the line you made that goes through the opposite vertex.
What is the value of ? Explain your reasoning.