Let A (-2, 3), B(8,3), C(6, 7).
(AB)2=(8+2)2+(3−3)2=102+02=100
(BC)2=(6−8)2+(7−3)2=(−2)2+42=20
(AC)2=(6+2)2+(7−3)2=82+42=80
Now, (BC)2+(AC)2=20+80=100=(AB)2
By converse of Pythagoras’ theorem
Therefore, Points A, B, C are the vertices of a right triangle.