Question

The length of the projection of $2\hat{i}-3\hat{j}+\hat{k}$ in the direction of $4\hat{i}-4\hat{j}+7\hat{k}$ is

• A. 3
• B. 9
• C. $3\sqrt{3}$
• D. 27

Answer 1

The correct option is A 3

Length of the projection of a on b is $\frac{|a.b|}{|b|}=\frac{|8+12+7|}{\sqrt{16+16+49}}=\frac{27}{9}=3$