Circles and squares

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edgey
Posts: 14
Joined: Sat Oct 10, 2009 6:34 pm UTC

Circles and squares

Postby edgey » Sun Oct 18, 2009 8:55 pm UTC

Hello, this is my first post on the xkcd boards :)

My problem is such (not so much homework but just something I am reading into)
Image

I need to find the length of "x" (in terms of r).

The way I am approaching it is to use the right angled triangle in figure 2.
I can use this and say that

(r+x)^2 = r^2 + r^2
(r+x)^2 = 2r^2
(r+x) = sqrt(2)r
x = r(sqrt(2) - 1)

Is there any obvious error here? Thank you in advance. I have a complete problem and my answer isn't very.. elegant. Want to make sure the basics are fine.

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Anubis
Posts: 222
Joined: Sun Mar 01, 2009 7:59 am UTC

Re: Circles and squares

Postby Anubis » Sun Oct 18, 2009 9:20 pm UTC

Your answer is correct.


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