CameraIcon
CameraIcon
SearchIcon
MyQuestionIcon
MyQuestionIcon
0
You visited us 0 times! Enjoying our articles? Unlock Full Access!
Question

The angle of elevation of a jet plane from a point A on the ground is 60. After a flight of 30 seconds, the angle of elevation changes to 30. If the jet plane is flying at a constant height of 36003 metres, find the speed of the jet plane.

Open in App
Solution

Let A be the point of observation and let AX be a horizontal line through A and QCAX. Let P and Q be the two positions of the plane. Let PBAX.



Then, PB=QC=36003 metres, BAP=60 and BAQ=30

From right ΔABP, we have

ABBP=cot 60=13AB36003=13

AB=36003×13m=3600 m ...... (i)

Let BC=PQ=x metres

Then, AC=AB+BC=(x+3600) m [using (i)]

From right ΔACQ, we have

ACCQ=cot 30=3x+360036003=3

x+3600=(3600×3)=10800

x=108003600=7200

Thus, PQ = 7200 metres

Now, 7200 m is covered in 30 seconds.

speed of the jet plane =(720030×60×601000)km/hr

=864 km/hr.

Hence, the speed of the jet plane is 864 km/hr.

flag
Suggest Corrections
thumbs-up
0
Join BYJU'S Learning Program
similar_icon
Related Videos
thumbnail
lock
Solution of Triangles
MATHEMATICS
Watch in App
Join BYJU'S Learning Program
CrossIcon