On the calculation of coordinate vector If the vectors a = (2,3, - 1) and B = (- 2,1,3), then the area of a parallelogram with a and B as adjacent sides?

On the calculation of coordinate vector If the vectors a = (2,3, - 1) and B = (- 2,1,3), then the area of a parallelogram with a and B as adjacent sides?

cosa=a*b/(|a|*|b|)
sina=√1-(cosa^2)
S=1/2absina*2=absina