A navy captain going away from a lighthouse at the speed of 4[√3 - 1]m/s. He observes that it takes him 1 minute to change the angle of elevation of the top of the lighthouse from 60° to 45°. What is the height (in meters) of the lighthouse?
Show answer & explanation
Correct answer: A
Explanation
The correct answer is option 1 ie 240√3.
Time taken is 1 min
Speed = 4 (√3 - 1)m/s
Distance = 60 × 4 (√3 - 1)
= 240(√3 - 1)
x = 240
height = x × √3
= 240√3