The angle of elevation of a jet plane from a point A on the ground is 600.After a flight of 15 sec,the angle of elevation changes to 300.If the jet plane is flying at a height of 1500 root 3 m,find the speed of the jet plane.

Dear Student!

Here is the answer to your query.


Let P and Q be the two positions of the plane and A be the point of observation. Let ABC be the horizontal line through A. It is given that angles of elevation of the plane in two positions P and Q from a point A are 60° and 30° respectively.

∴ ∠PAB = 60°, ∠QAB = 30°. It is also given that PB meters

In ΔABP, we have

In ΔACQ,we have

∴ Distance = BC = AC – AB = 4500m – 1500m = 3000m

Thus, the plane travels 3000m in 15 seconds

Hence speed of plane



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