6
The proper term for an 11 sided polygon is a hendecagon (undecagon is a mix of latin and greek roots) and you can triangulate it with as many triangles as you like. There is a minimum number of triangles though. The smallest i could get is 9, but you might be able to get it smaller
The hendecagon is a polygon with eleven sides.
A hendecagon can have upto 5 pairs of parallel lines.
11Eleven.
there are six