Rotate geometry

[billi]

Good morning,
I have a question :
I want to rotate a geometry but to keep one of the point fixed.
Here for example, I want to rotate the surface but to keep the blue points as they were, at the orange point. I only want to move the line below: is there a way to do so?
Cheers,
Jules

[ftzuk]

Post. your. code.
Else define an axis at those points and use that axis for your rotation.