Create line on both sides of four points


I am trying to create a line using the points resulting from ‘divide curve’ as the midpoint, which means that i am extending the line on both side of the point.
But the resulting line is in different direction. I have attached grasshopper file. MSc project steel (10.2 KB)

Can someone please help me out ?

Thank you

Graft length input should work.

MSc project steel (12.6 KB)

Hah, it works. Thanks a lot !