Question

The number of vectors of unit length perpendicular to vectors $a=\hat{i}+\hat{j}$ and $b=\hat{j}+\hat{k}$, is

• A. infinite
• B. one
• C. two
• D. three

Answer 1

Answer: (C)

Vector which is perpendicular to vertors a and $b$, is $a\times b$ or $b\times a$.
Hence, two vectors are possible which are perpendicular to $a$ and $b$.