Q10 of 35 Page 219

From a point at the height 100 m above the sea level, the angles of depression of a ship in the sea is found to have measure 30. After some time the angle of depression of the ship has measure 45. Find the distance travelled by the ship during that time interval.

Let the ship travel from A to Bin given time. So, the distance travelled by ship is AB.



Suppose, the observation point is at O.


OC = 100 m


The angle of depressions of A and B from O are 30⁰ and 45⁰ respectively.


∠OAC = ∠XOA = 30⁰


∠OBC = ∠XOB = 45⁰


In ∆OCB,




BC = 100


In ∆OCA,






100 + AB = 173


AB = 173 – 100


= 73 m


The distance travelled by ship during the given time is 73 m.


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