If these are your points 4,5 5,6 and 7,2 then, yes it is a right triangle
Side 1 = sqrt( (4-5)^2 + (5-6)^2) = sqrt 2
Side 2 =sqrt( ((4-7)^2+(5-2)^2) = sqrt 18
Hypotenuse = sqrt( (5-7)^2 +(6-2)^2 ) = sqrt 20
side 1 ^2 + side2 ^2 = hyp^2 Yep, it is a right triangle!