# Prove , if x is a rational number , x ≠ 0 then , tan(x) is not rational

1. Jan 5, 2013

### Maths Lover

prove , if x is a rational number , x ≠ 0 then , tan(x) is not rational

this theorem was proved by a mathematician called Lambert ,
I search for the proof , any one knows it ?!

2. Jan 5, 2013

### pwsnafu

3. Jun 12, 2013

### JsStewartFan

Last edited: Jun 12, 2013