Area of a parallelogram with vector vertices

Find the area of the parallelogram whose vertices are $0$, $a$, $b$, and $a + b$, where $a$ and $b$ are the vectors ${a} = \begin{pmatrix} \phantom -2 \\ -6 \\ \phantom -5 \end{pmatrix} \quad \text{and} \quad {b} = \begin{pmatrix} -1 \\ -2 \\ \phantom -0 \end{pmatrix}.$