UPDATE on 10/31/2012– My answer is wrong. Eagle-eye commenters found two more triangles to add to my answer, which are pointed out in the comments, and below the gallery in the UPDATE sections.
I came across a brain teaser on Facebook that a friend had commented on, and I’m pretty much going to get obsessed with any brain teaser, so I had to give it a shot (or 3).
It went like this.
How Many Triangles are in the Picture Below?
I counted it at first and was sure I missed some, so I went back and tried it again and found a few more. Then, on my third try, I found what I believe is all of them. I checked a few more times and it’s all I can find.
Then, the poster of the facebook question displayed the answer to everyone as one less than what I had come up with. So, it bothered me enough that I decided to completely waste my time putting this together. The gallery shows how I found my answer.
UPDATE on 10/10/2012– Faruk pointed out in the comments I missed one more triangle. You combine 19+20+21+26.
UPDATE on 10/31/2012– Mr.Chinchie found another one! You combine 13+24+25+26+27+28. So the current answer is now 41 triangles. If anyone finds another, let me know!