# triangle puzzle

Could someone please explain this to me?

http://www.ebaumsworld.com/trigrid.html

My guess is that it’s an optical illusion.

I don’t think the diagonal of the triangles are exactly the same. It looks like the one on the bottom is slightly higher than the one on the top. See where the diagonal crosses each grid axis and you’ll see that the one on the bottom is slightly higher than the one on the top. I’m guessing that the triangle on the bottom has slightly more area than the one on the top (exactly 1 square bigger).

This has been answered many times before. Simply, it’s not a triangle. The top one is slightly concave. The bottom, slightly convex. The lines are thick enough to hide minor changes.

To see why, measure the side length ratios for the two internal “triangles” and for the big “triangle.”

So… I just checked the site again.

Tell me, did you try clicking on the link that says: “Click here to see peoples explanations here!”?

Ok, i was looking at it again, and you are right. They r not triangles. Just using simple trig, using Tan (opposite/adjacent) the green triangle comes to Tan=.4, and the red triangle comes to Tan=.375. The angles of the green and red triangle should be equal. Also, the tan of the green and red should be equal to the tan of the Large triangle which is around .38. The triangles are not triangles at all, but 2 straight sides and one curved side.