What do the lines mean that are on certain triangles. for example, a triangle would have a single dash at the bottom, two dashes on one side and three dashes on the other
Working with Equilateral Triangles
In a paragraph proof format, show why the angles of an equilateral triangle must measure 60 degrees.
posted by Anonymous
The dashes mean that the sides are all of different lengths. If two sides have the same length, then they will both have the same number of dashes.
As for the proof, it depends on what you have covered so far. Equal angles are opposite equal sides. Since all the sides are equal, then all the angles must be equal. Since the angles sum to 180 degrees (another proof you will need) they are each 60 degrees.posted by Steve