Let's draw the triangle to see what it looks like:



It looks as though angle B could be a right angle which would
make triangle ABC a right triangle.  To find out, we find the
slopes of AB and CB to see if they are opposite-signed reciprocals

To find the slope of AB

m =  =  =  =  =  =  = -9

Since the slopes   and -9 are opposite-sign reciprocals
of each other, that is, their product is -1, the lines AB and CB are
perpendicular, and that means that triangle ABC is a right triangle. 

Edwin