A circle.
There is only one line (or line segment) that can be drawn between two distince points.
One
Seven.
line segments
66 ( 12 nCr 2 )
Such polygon is called a heptagon.
11, I believe.
They can not be line segments on the same line, but they can both be line segments.
A square, a rectangle, a quadrilateral, or a trapezoid. (there's more, but I won't bore you)
twenty
congruent line segments- line segments that have the same lengths.