the angle of elevation of a jet plane from point a on the ground is 60 degree after a flight of 30 seconds the angle of elevation changes to 30 degrees at the jet plane is flying at a constant height of 3600 root 3 find the speed of a jet plane
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Let us suppose that
CD = y and DE = x
Now from triangle BED
tan 60 = BD/DE
=> √3 = 3600√3/x
=> x = 3600
Again from triangle ACE
tan30 = AC/CE
=> 1/V3 = 3600V3/CE
=> CE = 3600V3*V3
=> CE = 3600*3
=> CD + DE = 10800
=> x + y = 10800
=> 3600 + y = 10800
=> y = 10800 - 3600
=> y = 7200
Now from figure
AB = CD = 7200
So speed = distance/time
=> speed = 7200/30 = 240 m/s = 240 * (18/5) km/h
{If we convert m/s into km/h, we multiply 18/5, So 240 m/s = 240 * (18/5) km/h}
=> speed = 48 * 18 = 864 km/h
So speed of the aeroplane is 864 km/h
CD = y and DE = x
Now from triangle BED
tan 60 = BD/DE
=> √3 = 3600√3/x
=> x = 3600
Again from triangle ACE
tan30 = AC/CE
=> 1/V3 = 3600V3/CE
=> CE = 3600V3*V3
=> CE = 3600*3
=> CD + DE = 10800
=> x + y = 10800
=> 3600 + y = 10800
=> y = 10800 - 3600
=> y = 7200
Now from figure
AB = CD = 7200
So speed = distance/time
=> speed = 7200/30 = 240 m/s = 240 * (18/5) km/h
{If we convert m/s into km/h, we multiply 18/5, So 240 m/s = 240 * (18/5) km/h}
=> speed = 48 * 18 = 864 km/h
So speed of the aeroplane is 864 km/h
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