Triangles

A friend e-mailed around a group of us this puzzle. Naturally I stopped all activity that actually earns me money, and set about solving it.

It took me a while, and I had to recall my school day use of sine and cosine, But I think I worked it out. Try it for yourself. My answer is after the break.

The two (green and red) triangles have different angles and hence take up different volume/space. So the “missing” square comes from small fractions of the blocks with the hypotenuse running through them.

The larger triangle has an angle of 20.6 degrees and the smaller one 21.8 degrees, so the two of them together are not a straight line – they just look that way if you don’t look too closely.

I didn’t think to Google the answer, but having now done so, I find that I was correct.