I have a curve $ y = a sin( b(x + c) )+ d $, the sketch looks likes 
I'm able to calculate value of $a=\frac{max-min}{2}=1.5$, $d=2$ and $b=\pi$.
I need help solving $c$, I know it gives a horizontal shift to the function and can be solved now by forming an equation, my question is how can we solve it from the graph ? (how to identify horizontal shift, and hence find $c.$
Any help is appreciated.
Thank you, Arif
It looks like $c=-\frac{1}{2}+ 2n$ with $n \in \mathbb Z$.
You may for example observe that the minimum of $y$ is attained for $x=0$, and the min of $\sin(t)$ is attained for $t=-\frac{\pi}{2}+2n\pi$
So $\pi c=-\frac{\pi}{2}+2n\pi$ from where you can get $c=-\frac{1}{2}+2n$
You may take either $c=-\frac{1}{2}$ or $c=\frac{3}{2}$ (if you want it positive)