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

Explanation

In Fig. 2 (NCT).
23, (O) .
is the observation point at the ground . (A) and (B) are the positions of air craft for which ` /_AOB = 30^@`. Draw a perpendicualr ` OC` on ` AB`. Here, ` OC = 3400 m` and ` /_ AOC = /_COB= 15^@`. Time taken by aircraft from (A) to (B) is ` 10 s`.
In ` Delta AOC, AC + CB = AC + AC = 2 AC = 2 xx 910 . 86 m`
Speed of the aircaraft, ` v= (distance AB0/ (time) = ( 2xx 910 . 86)/(10)`
` = 182. 17 ms^(-1)` = 18 2.2 ms^(-1)` .