Assertion (A) : Vector component of $\overline{\mathrm{b}}$ perpendicular to $\overline{\mathrm{a}}$ is $\frac{\overline{\mathrm{a}}\times (\overline{\mathrm{b}}\times \overline{\mathrm{a}})}{{\left|\overline{\mathrm{a}}\right|}^2}$

Reason (R) : $\overline{\mathrm{a}}\times (\overline{\mathrm{b}}\times \overline{\mathrm{c}})=(\overline{\mathrm{a}}·\overline{\mathrm{c}} )\overline{\mathrm{b}}-(\overline{\mathrm{a}}·\overline{\mathrm{b}})\overline{\mathrm{c}}, |\overline{\mathrm{a}}\times \overline{\mathrm{b}}|=\left|\overline{\mathrm{a}}\right|\left|\overline{\mathrm{b}}\right| \sin \mathrm{\theta }.$

The correct answer is