Answer: (1, 2)
Explanation:
There are many possibilities for the third point in the first quadrant
The simplest case is drawing a line parallel to x axis from point A and drawing a line parallel to y axis from point B and see where they intersect
The two lines would be:
y=2, x=1
So the point of intersection is (1,2) and they intersect at right angle hence qualify as a third point
Therefore, one possible location for third point is (1,2)