# Thread: Circular Functions & Trig

1. ## Circular Functions & Trig

With this second one, I understand why sine x cannot equal 0 but I do not understand/have no idea what kpi is

2. Hello juliak

The comments in red are correct: it should read
$\tan\theta =\pm\tfrac12$
But I don't know what you mean by
Originally Posted by juliak

With this second one, I understand why sine x cannot equal 0
Is there any suggestion that $\sin x$ is equal to $0$?

Also
but I do not understand/have no idea what kpi is
I don't know what kpi stands for either. Where does it appear anyway?

3. Originally Posted by Grandad
Hello juliak

But I don't know what you mean byIs there any suggestion that $\sin x$ is equal to $0$?

AlsoI don't know what kpi stands for either. Where does it appear anyway?

4. Hello juliak
Originally Posted by juliak
OK. I now know what kpi is: $k \pi$. But I still don't see where $\sin x \ne 0$ is relevant in your original post.

However, what you have written here is easy to understand. If $\sin x \ne 0$, then $x$ cannot be a multiple of $\pi$. (Since the sine of all multiples of $\pi$ is zero.) In other words:
$\sin x \ne 0$

$\Rightarrow x \ne k\pi$, where $k$ is an integer

$\Rightarrow x \ne 0 + k\pi$
Have we cleared all this up now?