Question

Aeroplane isat the height of 80 m the angle of elevation is 45° flies always at the constant height after 2 second angle of elevation is 30 degree find the speed

Answer 1

tan 45°=AB/BC=80/BC=1

BC=80 m

tan 30°=AB/BD=80/(80+CD)=1/(3^0.5)

80+CD=80×(3^0.5)

CD=80(1.732-1)

=80×0.732

=58.56 m

speed=58.56/2 m/s

=29.28 m/s