Question

Let a vector $\vec{a}$ has a magnitude 9. Let a vector $\vec{b}$ be such that for every $(x, y) \in R \times R-\\{(0,0)\\}$, the vector $(x \vec{a}+y \vec{b})$ is perpendicular to the vector $(6 y \vec{a}-18 x \vec{b})$. Then the value of $|\vec{a} \times \vec{b}|$ is equal to:

• A. $9 \sqrt{3}$
• B. $27 \sqrt{3}$
• C. 9
• D. 81

Answer 1

Answer: (B)

$27 \sqrt{3}$

Answer 2

The correct option is (B): $27 \sqrt{3}$