

Another puzzle: what's the radius ... - RiderOfGiraffes
http://bp1.blogger.com/_snss6u0-WRI/R7s5fhRORmI/AAAAAAAABBg/aVXosGTztCw/s1600-h/Larry%27s-Circle-Puzzle.jpg

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RiderOfGiraffes
Prompted by the discussion here: <http://news.ycombinator.com/item?id=1013789>

The exchange started here: <http://news.ycombinator.com/item?id=1013929>

Image found here: <http://zenoferox.blogspot.com/2008/02/circle-puzzle.html>

Warning: spoilers.

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ErrantX
That's barely even a puzzle. It's more of an optical illusion

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RiderOfGiraffes
Lots of people take a _long_ time to get this one. It's what I call an STF
problem - Slap the Forehead." Unless you see it instantly, when you _do_ see
it you are so frustrated ...

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alex_c
Argh. Yes, that's exactly how I felt when I finally got it. :p

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danek
me too. wow, it's sooooo simple. the trick is to not think.

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klodolph
Okay, this one is just... too easy. I can see why some people might find it
confusing, though.

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tlipcon
Without knowing that the + centers on the circle, is this actually possible?

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mitko
No.

Take any circle that passes through the loweset point (under the 3" mark) and
the right angle vertex that is down and left of the blue line.

Keep anything else fixed. This way infinitely many such constructions were
created, and the radii were different.

