Answer:
vertex C could be at (6,0) or (2,8)
(I'm sorry if I'm wrong, but if not I hope this helps!)
Explanation:
vertex C needs to be placed somewhere on the graph where it would form a right angle (and therefore a right-angled triangle as well). vertex C could be at (6,0) or (2,8). this is because at these two points vertex C will form a right angle, therefore making it a right-angled triangle.