Uh oh! Wolfram|Alpha doesn't run without JavaScript.
Please enable JavaScript. If you don't know how, you can find instructions
here
.
Once you've done that, refresh this page to start using Wolfram|Alpha.
x = √ ( (R/2 + r/4) ^2 - R*r - r^2/4 ) + R/2 + r/4
Natural Language
Math Input
Extended Keyboard
Examples
Upload
Random
