We have,
Given three vectors
Let,
−−→OA=2ˆi−ˆk
−−→OB=ˆi−3ˆj−5ˆk
−−→OC=3ˆi−4ˆj−4ˆk
So,
−−→AB=−−→OB−−−→OA
−−→AB=(ˆi−3ˆj−5ˆk)−(2ˆi−ˆk)
−−→AB=−ˆi−3ˆj−4ˆk
−−→BC=−−→OC−−−→OB
−−→BC=(3ˆi−4ˆj−4ˆk)−(ˆi−3ˆj−5ˆk)
−−→BC=2ˆi−ˆj+ˆk
−−→CA=−−→OA−−−→OC
−−→CA=(2ˆi−ˆk)−(3ˆi−4ˆj−4ˆk)
−−→CA=−ˆi+4ˆj+3ˆk
Now,
∣∣∣−−→AB∣∣∣=√(−1)2+(−3)2+(−4)2
∣∣∣−−→AB∣∣∣=√26
∣∣∣−−→BC∣∣∣=√22+(−1)2+12=√6
$\begin{align}
∣∣∣−−→CA∣∣∣=√(−1)2+42+32
∣∣∣−−→CA∣∣∣=√1+16+9=√26
Now,
AB=CA
Hence, it is a isosceles triangle.