Question

how to prove A=(-6,3); B=(3,-5); C=(-1,5) is a right triangle

Answer 1

Graph these points

Answer 2

and line connect them

Answer 3

Method 1: Solve for the measurements of each side, using the distance formula.
If the measurements follow the Pythagorean theorem, then it is a right
triangle

Method 2: Solve for the slopes of each side, If the product of the slopes of 2
sides = -1, then they are perpendicular (forming a 90degree angle.

The sides are AB, BC and AC