Displaying Category Posts

I know this is simple, but when i am looking at single.php and an individual post, i want to display the most recent 5 posts in that category. But it obviously has to be dynamic so it knows which category your in, how do i do this?

I have this and it doesn’t work; it displays posts from all categories:

$cat = get_query_var(‘cat’);
global $post;
$myposts = get_posts(‘numberposts=5&offset=1&category=$cat’);