How to set v in ReflectionTransform[v,p]?

Reflect Green Line about Blue Reflection Line, GreenPoint P is center of reflection. GreenPoint P’s coordinate is known.

After use

ReflectionTransform[v,GreenPoint]

I want to get this image. How to set v in ReflectionTransform[v,p]?
Blue line L’s equation is

y = -Sqrt[3]x + 15

line L’s slope is -Sqrt[3].