# Math Help - sine graph

1. ## sine graph

i am supposed to find the equation for this graph, (attached)
in the form of f(x)= asin(bx+c)

i have the hardest time at drawing graphs. i know how to find the amplitude (which is 2 here) and i know that the period=2pi/B (so the period is pi here. but i cant seem to figure out how to find the phase shift or how to draw the entire graph from just an equation. does anyone have any tips?

2. Originally Posted by elizabeth292
i am supposed to find the equation for this graph, (attached)
in the form of f(x)= asin(bx+c)
This needs to be clearer:

$f(x)\ =\ a.sin(b.x+c)$
should do. The problem is that $asin$ is often used to
denote the $arcsin$ function.

i have the hardest time at drawing graphs. i know how to find the amplitude (which is 2 here) and i know that the period=2pi/B (so the period is pi here. but i cant seem to figure out how to find the phase shift or how to draw the entire graph from just an equation. does anyone have any tips?
Your amplitude is OK, but the period is wrong. It is true that the
period of $f(x)$ is $2\pi/b$, but in your plot
the period is 2, so:

$b\ =\ \pi$
Now $f(0)\ =\ 1.8$ so:

$2.sin(c)\ =\ 1.8$.
So any solution of:

$c\ =\ arcsin(0.9)$
will be a solution for the phase, presumably you want one in
either $(-\pi, \pi]$ or $[0,\ 2 \pi)$.

RonL