An aircraft is flying at a height of `3400 m` above the ground, If the angle subtended at a ground observation point by the aircraft positions `10 s` apart is ` 30^@`, what is the speed of the aircraft ?

Options

A. ` 192 ms^(-1)`
B. ` 182 ms^(-1)`
C. ` 172 ms^(-1)`
D. ` 203 ms^(-1)`

Answer

B

Explanation

Refer to Fig. 2 (CF) . 57, ` OC= 3400 m,
/_AOC = /_COB = 15^@`
.
Time taken by airrcraft from ` A` to ` B= 10 s`
Here, ` AB = 2 AC = 2 xx OC tan 15^@`
` = 2 xx 3400 xx 0. 268= 18 22 .4 m`
Speed of aircraft, ` v= (1822.4)/(10)` ,brgt `= 182.24 ms^(-1)~~ 182 ma^(-1)`.