Find the area of the triangle formed by O, A, B when

Given and are two adjacent sides of a triangle.

Recall the area of the triangle whose adjacent sides are given by the two vectors and is where

Here, we have (a₁, a₂, a₃) = (1, 2, 3) and (b₁, b₂, b₃) = (–3, –2, 1)

Recall the magnitude of the vector is

Now, we find.

Thus, area of the triangle is square units.