Investigating the Sum of Polygon Interior Angles
Use the segment tool to triangulate each polygon: Pick ONE vertex and draw all of the possible diagonals from that ONE vertex. This will divide the polygon into multiple triangles.
How many triangles?
Compare the number of triangles created in each polygon to the number of sides in the polygon. What pattern do you notice?
How many degrees?
We know that there are 180˚ in every triangle. How can you use this to help you figure out how many total degrees are inside each polygon (interior angle sum)?
Try it out....
What is the sum of the interior angles of a pentagon?