The area of the parallelogram spanned by the given vectors is equal to the magnitude of their cross product.
(i + j + k) × (-2i + 3j + k)
= -2 (i × i) - 2 (j × i) - 2 (k × i)
… + 3 (i × j) + 3 (j × j) + 3 (k × j)
… + (i × k) + (j × k) + (k × k)
= - 2 (j × i) - 2 (k × i) + 3 (i × j) + 3 (k × j) + (i × k) + (j × k)
= 2 (i × j) - 2 (k × i) + 3 (i × j) - 3 (j × k) - (k × i) + (j × k)
= 5 (i × j) - 3 (k × i) - 2 (j × k)
= 5 k - 3 j - 2 i
Then the area of the parallelogram is
||-2 i - 3 j + 5 k|| = √((-2)² + (-3)² + 5²) = √38
