Sunday, October 10, 2010

circle puzzle

here's a clever little puzzle for everyone to ponder. without measuring and using only the information on the image, can you figure out the radius of the circle?


please dont give away the solution in the comments, but feel free to share how long it took you or other puzzles you have enjoyed!

via The Marcos Kirsch Experience®

12 comments:

Anonymous said...

I think I've got it, and it took me about thirty seconds. I could be wrong of course. I'm not great at this sort of thing. But it does seem obvious. =P

Zen said...

About 15 minutes for me, I think.

But I felt stupid when it clicked for me.

Sojourner said...

2 minutes...

Nick said...

When I first saw this puzzle years ago, I think I spent about 30 seconds trying to apply Pythagoras, before shouting "Eureka!" ;-)

Anonymous said...

It took me about 1 second - but then, I do have a mathematics degree

astropixie said...

i admit, it took me a little while to get find the solution. i was thinking too hard about it, then felt a little silly after i spotted the simple answer!

amydove said...

I was thinking WAY too hard about it, then read the comments about how easy it was, then immediately saw it.

celeph said...

hahaha... this could have taken a second but I started off thinking and calculating way too hard as well before it finally clicked :) Brilliant!

Aaron Walton said...

Tried to work it out the hard way and realized it was WAY simple.

Nice way to make yourself feel smart and stupid at the same time.

Anonymous said...

5 seconds max! It takes an Architect!

Cecilia said...

"Well, but isn't it of course....? What am i missing here?" was my thougt.
But then I realized i was right.
(-:

Eric J. Anderson said...

About 20 seconds for the mathematical solution...and then a little smile two minutes later when I saw the elegantly simple visual cue.