Answer:
the fourth vertex is D(2,5).
Explanation:
A rectangle has vertices at these coordinates A(-6, 3), B(-6, 5), C(2, 3).
Suppose the fourth vertex is D(x, y).
Then to make a rectangle, AB = CD.
√{(-6 - -6)² + (5 - 3)²} = √{(x-2)² + (y-3)²}.
√{(-6 + 6)² + (5 - 3)²} = √{(x-2)² + (y-3)²}.
√{(0)² + (2)²} = √{(x-2)² + (y-3)²}.
So x-2=0 and y-3=2
x=2 and y=5.
Hence, the fourth vertex is D(2,5).