Question

Let ABC be a triangle, the position vectors of whose vertices are `7hatj+10hatk,-1hati+6hatj+6hatk` and `-4hati+9hatj+6hatk`. Then, `DeltaABC` is
A. isosceles
B. equilateral
C. right angled
D. none of these

Answer 1

Correct Answer - A::C
We have, `AB=-hati-hatj-4hatk,BC=-3hati+3hatj`
and `CA=4hati-2hatj+4hatk`.
therefore, `|AB|=|BC|=3sqrt(2) and |CA|=6`.
Clearly, `|AB|^(2)+|BC|^(2)=|AC|^(2)`
Hence, the triangle is right angled isoscels triangle.