Question:
Mark $(\sqrt{)}$ against the correct answer in each of the following:
What is the projection of $\vec{a}=(2 \hat{j}-\hat{j}+\hat{k})$ on $\overrightarrow{\mathrm{b}}=(\hat{\mathrm{i}}-2 \hat{\mathrm{j}}+\hat{\mathrm{k}})$ $?$
A. $\frac{2}{\sqrt{3}}$
B. $\frac{4}{\sqrt{5}}$
C. $\frac{5}{\sqrt{6}}$
D. none of these
Solution:
