Convex vs. Concave
According to the 2nd applet, how would you describe what it means for a polygon to be convex? How would you describe what it means for a polygon to be concave?
Take another look at the 1st applet. How could you define the terms convex and concave with respect to the segment "inside" the polygon?
Is it ever possible for a triangle to be concave? Why or why not?