The full question is uploaded here: http://imgur.com/EZekb
Basically, given the graph shown in the image above, I thought that the limit of $\sin(f(x))$ would be $\sin(2)$, since the limit of just $f(x)$ is $2$. However, my teacher says that it is $\sin(3)$, since $f(x) = 3$ at that point. Can anyone explain why it is one and not the other?
Also, if you could provide a source, that would be great, so I can show my teacher if I am right.