Perpendicular Lines

Question

The vertices of a triangle are labeled clockwise A(–5, 3), B(6, 1), and C(–2, –3). How could you show that the figure is a right triangle?

 

Answer 1

sketch a rough graph of the 3 points, connected with lines AB, AC and BC

Angle C looks like a likely 90 degree angle.

Calculate the slopes of AC and BC. to be a right angle those slopes must be negative inverses.

While "close" they aren't. -2 and .2 are not negative inverses.