urgent!!!!! finding co-ordinates in squares A(7,2) and C(1,4) are vertices of a square ABCD. equation BD is y=3x-9 midpoints AC: (4,3) find the co-ordinates of B and D i just dont understan how to get the co-ordinates, ive tried plotting a graph but to no avail. i found the midpoints and the equation listed above with relative ease but this part of the question just baffles me. if anyone could just explain the method of this kind of task, i will be able to answer the question. thank you.