Thanks for your answer. But how do I solve for those 4 vars.(a,b,c,d) with only one equation. And what is t in last equations. I really do not know how to convert this to Code because I do not understand most of the steps.

Ok thanks. What do you mean with equation of intersection. If I am not wrong two triangles intersect at a line.(without some edge cases like same Plane.) I want to know the line at which those two triangles intersect. Thanks for all your help till now. SORRY for my spelling mistakes.

I will try to implement this now. I could take its time. I will Post the my code later. Thanks for all your help.

Sorry for my mistake. Line goes from 1 to 2. Everything else should be right.