Mathematics · 2021
JEE Main · 25 February 2021, Shift 1 · Q79
A man is observing, from the top of a tower, a boat speeding towards the tower from a certain point A, with uniform speed. At that point, angle of…
A man is observing, from the top of a tower, a boat speeding towards the tower from a certain point A , with uniform speed. At that point, angle of depression of the boat with the man's eye is $\displaystyle 30^{\circ}$ (Ignore man's height). After sailing for $\displaystyle 20$ seconds, towards the base of the tower (which is at the level of water), the boat has reached a point B , where the angle of depression is $\displaystyle 45^{\circ}$. Then the time taken (in seconds) by the boat from B to reach the base of the tower is :
Official answer
(2)
$\displaystyle 10(\sqrt{3}+1)$
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JEE Main 2021 Mathematics question, with the answer from NTA’s final answer key. Where our answers come from.