CONCAVE VS. CONVEX

As you can see concave shapes have a place that slopes inwards almost like a hole in the shape.  Convex shapes are complete with no holes.

See the difference?

Contact lenses can be an example of concave and convex.

If you see a shape slope inwards at any degree the probability of it being concave increases.  See the slope in the concave angle.  It's almost like you could draw a dotted line from the top to the bottom to make it a real shape (rectangle).  The oval is complete with no gaps and we could not draw a dotted line from the top to the bottom and have empty space.


Here is a trick question.  Is this heart concave or convex?

It's Concave!
 Why?  Because if you draw a line from one curve of the heart to the other you can find empty space or gaps between the two curves.