Explanation:
place point first. (1, -1) then go up 2 and to the right 3 for the next point. (4,1) keep going up 2 right 3.
to find other side of line, start at (1, -1) go down 2 to the left 3 (-2,-3) and down 2 left 3 again.
the line should go towards the top right box and down towards bottom left