Answer:
To find all coordinates, we just need to observe the graph.
The coordinates of point C are (2c,d). From the graph, we notice that the x-coordinate of C is the same x-coordinate of V, because they are in the same vertical lines.
The coordinates of point D are (c,0). The problem states that D is a mid point, so basically its coordinate is half of point's V, which is c.
The slope of both AB and DC is d/c. The slope is the fraction between y-coordinate and x-coordinate. If you we calculate the slope of DC, we would have d as vertical coordinate and c as horizontal coordinate.
The slop of both AD and BC is -b/c-a. The slope between the points A(a,b) and D(c,0) is