The angle of elevation of a jet plane from a point A on the ground is 60o .After a flight of 30 seconds , the angle of elevation changes to 30o .If the jet is flying at a constant height of 3600root3, find the speed of the jet plane.
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Let D and E be the initial and final positions of the plane respectively
Consider the ΔABD
tan60=BD/AB
√3=1500√3/AB
AB=1500
Consider the ΔACE
tan30=CE/AC
1√3=1500√3/AC
AC=4500
BC = AC - AB
= 4500 - 1500
= 3000 m
DE = BC = 3000 m
So the plane travels a distance of 3000m in 15 seconds.
Therefore, speed of the plane =3000/15
= 200 m/s
Consider the ΔABD
tan60=BD/AB
√3=1500√3/AB
AB=1500
Consider the ΔACE
tan30=CE/AC
1√3=1500√3/AC
AC=4500
BC = AC - AB
= 4500 - 1500
= 3000 m
DE = BC = 3000 m
So the plane travels a distance of 3000m in 15 seconds.
Therefore, speed of the plane =3000/15
= 200 m/s
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