How many different lines can you draw through 4 points?

Consider on the plane the possible locations of 4 points and try to investigate how many lines can be drawn through them.

1. Suppose that all four points are located in a straight line, that is, only one straight line can be drawn.

2. Suppose there are three points in a row and one to the side. Then through three points we draw one straight line, and then from a point lying to the side we draw three more straight lines through three points lying on one straight line. We get 4 straight lines.

3. Suppose that on the plane 4 points are located so that they form a quadrangle of any shape. Then we have – 4 lines – sides of a quadrangle and 2 diagonals. There are 6 straight lines in total.