# Thread: inverse trig function help,

1. ## inverse trig function help,

Without using a calculator, work out, giving your answer in terms of $\displaystyle \pi$ , the value of;

$\displaystyle arctan ( -\frac{1}{\sqrt{3}} )$

I know how to work out arcsin and arccos, by looking at the x and y values on the unit circle, but how do I work out acrtan? because the way I understand it is that tan = sin/cos which is equal to y/x.

Can someone please explain how to work this out?

thanks.

2. Originally Posted by Tweety
Without using a calculator, work out, giving your answer in terms of $\displaystyle \pi$ , the value of;

$\displaystyle arctan ( -\frac{1}{\sqrt{3}} )$

I know how to work out arcsin and arccos, by looking at the x and y values on the unit circle, but how do I work out acrtan? because the way I understand it is that tan = sin/cos which is equal to y/x.

Can someone please explain how to work this out?

thanks.
Solve $\displaystyle \tan \theta = - \frac{1}{\sqrt{3}}$ where $\displaystyle -\frac{\pi}{2} < \theta < 0$.