Another little puzzle

[xmastree]

Unlike the previous one, you don't have to be John Nash to figure it out

http://i50.photobucket.com/albums/f341/chrispollard/wtf-1.jpg

It's a crappy mobile phone picture, so excuse the quality.

The question is, where does the 'hole' at the bottom come from?

[Datech]

It deals with the slope of the triangles. The red triangle's slope is 3/8, or .375, while the green triangle is 2/5, or .4. This is evident by that little voice in the back of your head telling you the top drawing bows in while the bottom drawing bows out.

Therefore, the entire drawing isn't really a triangle since the two interior triangles have different slopes. This makes the entire drawing a polygon which allows it to be rearranged as so with with same area.

[Oneslowz28]

I remember doing that puzzle in middle school.

[luciusad2004]

Man, this kinda stuff is so cool, Everytime I see these awesome little puzzles I wish i was better at math.