Reflect the point (5,5)(5, 5)(5,5) across the line y=xy = xy=x.
(5,5)(5, 5)(5,5)
(−5,−5)(-5, -5)(−5,−5)
(5,−5)(5, -5)(5,−5)
(−5,5)(-5, 5)(−5,5)