Let r , a , ~b and c be four non–zero vectors such that r a =0, | r b |=| r || b |,| r c…

Let \(\overrightarrow{\mathrm{r}}, \overrightarrow{\mathrm{a}}, \overrightarrow{\mathrm{~b}}\) and \(\stackrel{\rightharpoonup}{\mathrm{c}}\)be four non–zero vectors such that \(\overrightarrow{\mathrm{r}} \cdot \overrightarrow{\mathrm{a}}=0,\) \(|\overrightarrow{\mathrm{r}} \times \overrightarrow{\mathrm{b}}|=|\overrightarrow{\mathrm{r}}||\overrightarrow{\mathrm{b}}|,|\overrightarrow{\mathrm{r}} \times \overrightarrow{\mathrm{c}}|=|\overrightarrow{\mathrm{r}}||\overrightarrow{\mathrm{c}}|,\)then [a b c] =