Altitude (height above sea level)
Elevation contour lines.
there are 6 lines can pass through 4 noncollinear points.
1
Just one.
exactly one
There is exactly one line that can pass through two distinct points. This line is uniquely determined by the two points.
The lines that pass through points 4 -6 2 -3 and 6 5 3 3 on a grid are the lines y=x.
There is only one possible line that can can through two different points, presuming there are no overlaps.
It has 8. Each passes through the centre. Four pass through vertices, four pass through the mid-points of opposite sides. 4
There is only one possible line that can can through two different points, presuming there are no overlaps.
They are intersecting lines.
They are intersecting lines.