This section requires Javascript.
You are seeing this because something didn't load right. We suggest you, (a) try
refreshing the page, (b) enabling javascript if it is disabled on your browser and,
finally, (c)
loading the
non-javascript version of this page
. We're sorry about the hassle.
1 solution
There are 3 different sizes of triangles :-
There are 1 2 triangles of the smallest size , 6 of the middle size , 2 of the biggest size , the sum is 2 0 .