The angle of elevation of a jet plane from a point A on the ground is 60 ° . After a flight of 20…

The angle of elevation of a jet plane from a point A on the ground is 60°. After a flight of 20 seconds at the speed of 432 km/hour, the angle of elevation changes to 30°. If the jet plane is flying at a constant height, then its height is:
  1. 12003 m
  2. 24003 m
  3. 18003 m
  4. 36003 m

Solution

tan60°=hy

3=hy⇒h=3y …1

tan30°=hx+y

13=hx+y⇒3h=x+y …2

Speed 432 km h-1⇒432×2060×60⇒125 km

3h=125+y

3h-125=y

from 1

h=33h-125

h=3 h-1235

h=635 km

h=12003 m

Asked in: JEE Main 2021 (24 Feb Shift 2)

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