<PRE><B>Question 870219</B>
A plane is approaching your home, and you assume that it is traveling horizontally at approximately 850km per hour. If the angle of elevation of the plane is 20 degrees at one time and one minute later is 55 degrees, find the altitude of the plane. 

height of plane = h
angle of elevation = 20 degrees
x the ground distance
tan 20 = h/x
x=h/tan 20

speed of plane 850 km/h
1 minute = 1/60 hour the plane travels 850*1/60=14.17 km
ground distance now will be (x-14.17)
tan55 = h/(x-14.17)
x-14.17 = h/tan 55

x= 14.17 +h/tan 55

14.17 +(h/tan 55)=h/tan 20

h/tan 20 -h/tan 55 =14.17
2.75h-0.7h=14.17
2.05h=14.17
h=14.17/2.05
h=6.912 km

height = 6912 m</PRE>