1.2. In figure a, 7 lines intersect at 7 points, in figure b- at 9 points. Can 7 lines intersect at 8 points? How many points of intersection can 7 lines have in general? (List all possible values.)
1.2. There may be no points of intersection, there may be one or any number from 6 to 21. We provide an example with 8 points of intersection: 6 lines running along the sides and diagonals of the trapezoid, and one more line parallel to the bases and passing through
the point of intersection of the diagonals. Find the other examples yourself.