Question

Plzz give the answer

Answer 1

According to me, the speed of aeroplane should be 864 km/hr...

Answer 2

let p be the position of the observer
let c be position of plane and
a be the position of plane after 30 sec
AB=CD=3600√3
angle APBand CPD are angles of elevation
APB=30 and CPD=60
B=D=90
ABCD is a rectangle
AC=BD
in Triangle CPD
tan60=CD÷PD
√3=3600√3÷PD
PD=3600m
now
$\tan(30 ) = ab \div bp \\ 1 \div \sqrt{3 } = 3600 \sqrt{3} \div bp \\ bp = 3600 \times 3 \\ bp = 10800m$
BD=BP-PD
BD=10800-3600
BD=7200m
therefore AC=7200m
now
$speed = distance \div time \\ speed = 7200 \div 30sec \\ speed = 240mper \: sec$