The correct option is C ABC forms an obtuse angled triangle.
Given : A≡(3,4),B≡(−3,2),C≡(−5,−4)
AB=√36+4=2√10 units
BC=√4+36=2√10 units
AC=√64+64=8√2 units
Checking the condition for formation of a triangle,
AB+BC>ACAB+AC>BCAC+BC>AB
So, it forms a triangle.
Now, AC2=128,AB2=40,BC2=40
AC2>AB2+BC2
Hence, ABC is an obtuse angled triangle.