Answer:
Use photo math, it will explain all the steps
The answer is C.
This is because 7 must be greater than 12-g.
G cannot equal 5 and below because 12-5=7.
Therefore C is the only answer that works.
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.