Mathematics

Problem

\mathbf{a}, \mathbf{b}, \mathbf{c}

and

\mathbf{p}, \mathbf{q}, \mathbf{r}

are reciprocal system of vectors, then

\mathbf{a} \times \mathbf{p} + \mathbf{b} \times \mathbf{q} + \mathbf{c} \times \mathbf{r}

is equal to a.

[\mathbf{a} \mathbf{b} \mathbf{c}]

[\mathbf{p} + \mathbf{q} + \mathbf{r}]

c. 0 d.

\mathbf{a} + \mathbf{b} + \mathbf{c}