tan-1(x)=7/11

Yes, I didn't notice that - thanks Alan.

 I assume the question asker actually meant 

$$tan(x)=\frac{7}{11}$$

therefore 

$$x=tan^{-1}\left(\frac{7}{11}\right)$$

This is the question that CPhill answered but it is not actually the question that you asked!

tan-1(x)=7/11

---------------------------------------------------------------------------------------------------------------------------

We're just looking for an angle whose tangent = 7/11. Go to the on-site calculator, hit the 2^nd button, and then the "atan" button......key in your "7/11" and hit enter.

Note that this angle could also lie in the 3^rd quadrant, depending on the situation.

Ermm!  The equation says the angle whose tangent is x is 7/11.

so x = tan(7/11)   (presumably the angle is in radians.)

Or did the questioner mean tan(x) = 7/11, in which case Chris's answer is correct.