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.
find tan(A/2) if tan(A)=9/40
find tan(A/2) if tan(A)=9/40
Natural Language
Math Input
Extended Keyboard