In a previous post I talked about shapes of constant width. I didn't know of any other coins besides the UK 50p and 20p that had the property of being the same width all the way round without being circular.
Well I was recently given this coin instead of 20p:
It's a 50 Fil coin from United Arab Emirates. Or half a dirham. It's only about half a millimetre smaller than a 20p coin.
It got me thinking, how many other coins from around the world have this property. A quick google search revealed the Jamaica Dollar:
And the Austrian commemorative 5 Euro which, unusually, has 9 sides:
Do you know of any more? Let me know in the comments.
Tags: 50p, coins, magnet ball geometry, maths, solids of constant width
