# Thread: How to I Find Angle (and Vice Versa)

1. ## How to I Find Angle (and Vice Versa)

Hi, I have a question, according to the diagram shown below,

what is $x$ if the slope is known, (such as $\frac{5}{9}$). How do we find slope if we know $x$?
Note: Figure is not drawn to scale.

Thanks!

-Masoug

2. I don't understand your question - are you using $\displaystyle x$ to denote the angle made with the $\displaystyle x$ axis? Or are you using it to denote an $\displaystyle x$ coordinate?

If you are referring to an angle, you should use $\displaystyle \theta$.

3. The "slope" of a line is the tangent of the angle, $\frac{y}{x}= tan(\theta)$, so the angle is the inverse tangent:
$\theta= tan^{-1}(\theta)= arctan(\theta)$.

I don't understand the "vice-versa" part of your question. Your original question was "how do I find the angle" so "vice-versa" would be "how does the angle find me"!

4. Thanks for the quick replies. Sorry for the failed picture too...

What I meant by "vice versa" is if I know the angle, can I find the slope?

-Masoug