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.
tg(x)^2=(4 (a/c)^2 -1) / (1 +( a^2 / (r^2-c^2/4)))
Natural Language
Math Input
Extended Keyboard
Examples
Upload
Random