# Thread: Help with sinus functions

1. ## Help with sinus functions

Im having trouble understanding the sinus functions.
I understand that it is periodic with 360 degrees.

But I am having trouble findig top and bottom points and the point zero in
f.eks Sin 2x.

2. Originally Posted by Nordis
Im having trouble understanding the sine function.
I understand that it is periodic with 360 degrees.

But I am having trouble findig top and bottom points and the point zero in
f(x) = Sin 2x.

Hi Nordis,

The zeros of $\displaystyle y = \sin x$ (the values of x where sin x = 0) are at the multiples of $\displaystyle \pi$ and it is there that the graph crosses the x-axis. $\displaystyle \sin x$ has a maximum value of $\displaystyle -1$ at $\displaystyle \frac{\pi}{2}$ and a minimum value of $\displaystyle -1$ at $\displaystyle \frac{3\pi}{2}$ and all angles coterminal with them.

The values of sin x regularly repeat themselves every $\displaystyle 2\pi$ units. Thus, sin x has a period of $\displaystyle 2\pi$ (360 degrees).

Now, $\displaystyle y=\sin 2x$ means there are 2 periods in an interval of $\displaystyle 2\pi$

Finally, in $\displaystyle y=\sin 2x$, the 2 means that in an interval of length $\displaystyle 2\pi$, there are 2 periods. There will be 2 occilations every $\displaystyle 2\pi \ \ or \ \ 360^{\circ}$. The period will be $\displaystyle \frac{2\pi}{2}$ or $\displaystyle \pi$.