I have a figure containing a triangle and a rotated triangle superimposed at the centroid. I have joined two points of the resultant overlapped image created from the original and the rotated triangles. Now I want to do a reflection over this oblique line. I searched the internet but i cant find any equation. Eq. are provided for reflecting over x-axis, y-axis , over the line x=2 & over the line x=y but no equations are shown for reflecting object over an oblique line. One site gave the method to find the eq of line which was used to reflect the triangle but it didnt give any example for reverse case. Its link was:

http://www.rcboe.org/cms/lib010/GA01903614/Centricity/Domain/1030/Reflections.pdf

I have attached the figure. I want to reflect portions of the two triangles over the dark fat line.

Some body please guide me.

Zulfi.