[Closed] Excel Question

Can anyone help?

I've got a set of 20 co-ordinates in simple X,Y Format in 2 columns.
If you plot them in a scatter graph, you can see they form a circle of radius 12 around 0,0
However, the list is random.
I want to reorder them so they're sequential around the circle, say starting from 3 o'clock and going clockwise.

My initial idea was to calculate the angle from the x-axis using [i]atan[/i], and sort using the angle. But to cope with the negative values, its going to be a complex IF statement with 4 variables (from the 4 quadrants)

any other ideas?