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.
pi(21* 5/12) 21 + pi (21*5/12)^2
pi(21* 5/12) 21 + pi (21*5/12)^2
Natural Language
Math Input
Extended Keyboard