Machine-translated by Google. Questions are authored in English.
Top

Discussion

From a point P on a level ground, the angle of elevation of the top tower is 30º. If the tower is 100 m high, the distance of point P from the foot of the tower is:

  • A.149 m
  • B.156 m
  • C.173 m
  • D.200 m

Answer: C

The tower is opposite the \( 30^{\circ} \) angle and the distance is adjacent, so:

\[ \tan 30^{\circ} = \frac{100}{d} \quad\Longrightarrow\quad d = \frac{100}{\tan 30^{\circ}} = 100\sqrt{3} \]

\[ d = 100 \times 1.732 = 173.2 \approx 173 \text{ m} \]

A \( 30^{\circ} \) elevation always puts the observer \( \sqrt{3} \) times the height away. Multiplying by \( \tan 30^{\circ} \) instead of dividing gives about 58 m - the classic inversion.

No comment is present. Be the first to comment.
Loading…

Post your comment

Please log in or register to post a comment.