(b)
[image:12_image4.emf]
Let any point on second line be $(\lambda,\ 2\lambda,\ 3\lambda)$
$\cos\theta = \frac{6}{\sqrt{42}},\sin\theta = \frac{\sqrt{6}}{\sqrt{42}}$
$\Delta_{OAB} = \frac{1}{2}(OA)OB\sin\theta = \frac{1}{2}\sqrt{3}\ \lambda\sqrt{14} \times \frac{\sqrt{6}}{\sqrt{42}} = \sqrt{6}$
$\Rightarrow \lambda = 2$
So $B$ is (2, 4, 6)