The area is the given by the magnitude of the cross product of the side vectors. That value is
Area = ||u×v|| = ||u||·||v||·sin(θ)
where θ is the angle between the vectors.
The cross product of [1, -3, 2] and [0, 3, -1] is [-3, 1, 3}, which has magnitude
√((-3)² +1² +3²) = √19 ≈ 4.3589
