Multiple choice

The angles of depression of two points from the top of the tower are $\displaystyle 30^{\circ}$ and $\displaystyle 60^{\circ}$ If the height of the tower is 30 m then find the maximum possible distance between the two points (in m)

  1. $\displaystyle 20\sqrt{3}$
  2. $\displaystyle 30\sqrt{3}$
  3. $\displaystyle 40\sqrt{3}$
  4. $\displaystyle 50\sqrt{3}$
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C Correct answer
Explanation

The distance of the two points from the base of the tower are d1 = 30/tan(30) = 30*sqrt(3) and d2 = 30/tan(60) = 30/sqrt(3) = 10*sqrt(3). The maximum distance between the two points occurs when they are on opposite sides of the tower, which is d1 + d2 = 30*sqrt(3) + 10*sqrt(3) = 40*sqrt(3).

AI explanation

The maximum distance occurs when the two points are on opposite sides of the tower. Let the distances from the base to the points be x and y. Using the basic trigonometric ratio for the angle of depression, tan(60 degrees) = 30 / y, so y = 30 / sqrt(3) = 10 * sqrt(3) m. Similarly, tan(30 degrees) = 30 / x, which gives x = 30 * sqrt(3) m. The maximum possible distance is the sum of these distances, 10 * sqrt(3) + 30 * sqrt(3) = 40 * sqrt(3) m.