How do I get tan-1? (Probably a stupid question)

[Chriskoenig]

This is probably a simple question, but I cannot find the solution. I'm working on this program where I need to find an angle, and the only way I can see to do this with the information I have is to use tan-1. You know, the trig function that 'cancels out' tan (< tan-1(tan(x)) = x)? Anyway, it's summer, so I can't ask my math teacher how to get it through another way, like with sin(x)/(cos x) or something, so I'm in a rut. Please help!

 

[Guest_imported]

In QB, it's done using ATN(x). However, you need to watch out for the values it returns (for pi/2<=x<=3/2pi). You may need to add pi to your result value to get it in the range you want.