Slope of AB=(2-3)/(1+1)=-1/2; AC=(-1-3)/(-3+1)=-4/-2=2; BC=(-1-2)/(-3-1)=-3/-4=3/4.
The product of two sides that are perpendicular is -1. Slopes of AB and AC are perpendicular so angle A is a right angle. ABC is a right-angled triangle.
It is negative.
When you subtract a negative a positive number from a negative number, the result is positive. The equation can be rewritten as -8.8-(+3.4).
This is clearly false as it will just mess up the question.
