Question

Points A(3,9), B(1,1), C(5,3) and D(a,b) lies on the first quadrant and are the vertices of quadrilateral ABCD. A square is formed by joining the midpoints of AB, BC, CD and DA. What are the coordinates of point D?

Answer 1

well it always helps to draw out the problem first

Answer 2

I am not quite sure about the rest, it is kind of confusing.

Answer 3

I already figure out that one side of the square is \[\sqrt{10}\]
But I don't know how to find the coordinates of D