In a right angle $\triangle \mathrm{ABC}, \angle \mathrm{A}=90^{\circ}$ and sides a, b, c are respectively, $5 \mathrm{~cm}, 4 \mathrm{~cm}$ and $3 \mathrm{~cm}$. If a force $\vec{F}$ has moments 0,9 and 16 in $N$ cm. units respectively about vertices $A, B$ and $C$, then magnitude of $\vec{F}$ is

• A

  3
• B

  4
• Correct answer
  C

  5
• D

  9

Solution

$\mathrm{F} \cdot 3 \sin \theta=9$ $\mathrm{~F} \cdot 4 \cos \theta=16$ $\Rightarrow \mathrm{F}=5$

Hence, the correct answer is option: 'C'.