Thales' Theorem (c 550 BC) - The First-Ever Theorem Named after an Individual

[DonRocks]

Thales' Theorem (named after Thales of Miletus, and theorized about 2,500-years ago) is a remarkably simple, yet brilliant, piece of work:

1. You have a circle

2. You draw a line, making a diameter.

3. Form a triangle anywhere inside the circle, using that line (AC) as one of the sides.

4. No matter where you put point B, the angle ABC will be 90 degrees.

It's easily understood when visualized - go to the "Thales' Theorem" link. It's really quite beautiful, if math can be beautiful.

Thales' is also, alas, the first person ever to make an attempt at "cornering the market" on something (olive-oil presses - really!)

I feel badly that this is what inspired this thread. In ten years, people will be playing Tiddly Winks with Bitcoins, and I don't want anyone here to lose their shirts - take it from someone who lost 2/3 of his net worth in a stock market crash. (I made a good percentage before the crash, so it isn't all *that* bad, but I came out behind, and one thing I learned is that you don't know when something has collapsed, until after it has collapsed: Take. Your. Profits.)