To find the midpoint of AB, first find the coordinates of A and B
From the graph, A = (2,8) and B = (7, -5)
The midpoint of AB = 0.5 * { A + B }
so,
The midpoint of AB = 0.5 { (2,8) + (7, -5) }
= 0.5 * (9 , 3) = (4.5 , 1.5)
so, the coordinates of the midpoint = (4.5 , 1.5)
