# Independent Triangles with Straight Lines

Your task is to create independent triangles (which means they do not have the same edge) by drawing straight lines as exemplified below:

In this example, there are $5$ lines and $5$ independent triangles and no triangle exists with the same edge with another triangle.

so,

At least how many straight lines do you need to have $11$ independent triangles without having any triangle having the same edge as given above?

• Is Independent triangles means there is at least one edge that is not touched by another triangle? – rudra Dec 2 '17 at 14:04
• @rudra no edge is supposed to be common between two triangles at all in the graph. – Oray Dec 2 '17 at 14:06
• It seems 12 independent lines are required though they can form 12 such triangles instead of required 11 :-( – Mea Culpa Nay Dec 2 '17 at 14:30
• Doing some search Oray, isnt KOBON triangle same as what you are asking? – DEEM Dec 2 '17 at 14:58
• @DEEM yes :) but asking this as a question is a puzzle itself. – Oray Dec 2 '17 at 14:59