What Makes a Triangle a Triangle?

Can we use any three side lengths to make a triangle?

Try rearranging the lengths below to create a triangle. Use the green dots to rotate the segments and the blue dots to move the segments. Does it work? Why or why not?

What segment lengths DO make a triangle?

Use the green dots to change the length and position of sides a and b. Write down THREE side length combinations for sides a and b that work and three that do not work to make triangle ABC. Add these combinations together, do you notice anything?

At what point does the triangle stop being a triangle?

Use the green dot to change the dimensions of the triangle. Where is it NOT a triangle? At what point does it stop being a triangle?