Question 981369
What if you are just told what those two ways are?  Could you then show using those two ways?


(1)
Find the slopes of each pair of the points.  Look for any two slopes which are negative reciprocals of each other.


(2)
Find the distances between each pair of points  (Use the Distance Formula).  Identify the longest distance.  Form the equation such that the square of the longest distance is one member and the sum of the squares of the other two distances is the other member.  Compute each member.  The equation should be correct, IF the points form a right triangle.