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A kite is flying at a height of 75 m above the ground, attached to a string inclined at \( 60^{\circ} \) to the horizontal. The length of the string is:

  • A.50 √2 m
  • B.50√3 m
  • C.50m/√2
  • D.50m/√3

Answer: B

The string is the hypotenuse and the kite's height is opposite the \( 60^{\circ} \) inclination, so sine applies.

\[ \sin 60^{\circ} = \frac{75}{L} \quad\Longrightarrow\quad \frac{\sqrt{3}}{2} = \frac{75}{L} \]

\[ L = \frac{150}{\sqrt{3}} = \frac{150\sqrt{3}}{3} = 50\sqrt{3} \approx 86.6 \text{ m} \]

Rationalising \( \tfrac{150}{\sqrt{3}} \) into \( 50\sqrt{3} \) is what matches it to the listed form. The string must be longer than the 75 m height, which rules out the two divided options immediately.

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