Question

A man on a cliff observes a boat at an angle of depression of 30° which is approaching the shore to the point immediately beneath the observer with a unitorm speed. Six minutes later, the angle of depression of the boat is found to be 60°. Find the time taken by the boat to reach the shore. ​

Answer 1

Let OA be the cliff and P be the initial position of the boat when the angle of depression is 30°. After d minutes the boat reaches to Q such that the angle of depression at Q is 60°.

Then see the above attachments..

hope it helps..