The angle of elevation of the tip of a flag staff from a point 10 m due South of its base in $60^{\circ}$. What is the height of the flag staff correct to the nearest metre?

• A

  15 m
• B

  16 m
• Correct answer
  C

  17 m
• D

  18 m

Solution

$\begin{aligned} \tan 60^{\circ} & =\frac{x}{10} \\ \sqrt{3} & =\frac{x}{10} \\ x & =10 \sqrt{3}=10 \times 1.732 \\ & =17.32 \\ & \cong 17 .\end{aligned}$

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