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.
s/2=(a l sqrt(1+a^2 l^2)+sinh^(-1)(a l))/(4 a)
Natural Language
Math Input
Extended Keyboard
Examples
Upload
Random