Compute $| \mathbf { a } \times \mathbf { b } |$

Short Answer

Compute $| \mathbf { a } \times \mathbf { b } |$ if $| \mathbf { a } | = 3$ , $| \mathbf { b } | = 7$ , and $\mathbf { a } \cdot \mathbf { b } = \mathbf { 0 }$ .