1.
A vector of magnitude 51\sqrt{51} which makes equal angles with the vectors a=13(i^2j^+2k^)\vec{a} = \frac{1}{3}(\hat{i} - 2\hat{j} + 2\hat{k}), b=15(4i^3k^)\vec{b} = \frac{1}{5}(-4\hat{i} - 3\hat{k}) and c=j^\vec{c} = \hat{j}, is