question_answer

The angle of elevation of a jetfighter from a point P on the ground is\[\text{6}0{}^\circ \]. After five seconds of flight, the angle of elevation changes to\[\text{45}{}^\circ \]. If the jet is flying at a height of 3000 m. find the speed of the jet, in m/s.

A) \[1000(3-\sqrt{3})\]

B)        \[200(3-\sqrt{3})\]

C) \[1000\sqrt{3}\]               

D)        \[600\]

Correct Answer: B

Solution :

In \[\frac{bc}{\sqrt{{{b}^{2}}+{{c}^{2}}}}\]or \[\therefore \] In \[=\sqrt{64+36}\] or \[=\sqrt{64+36}\] \[=\sqrt{64+36}=10\,cm\] \[=\sqrt{64+36}=10\,cm\] \[\Rightarrow \]Speed of the plane \[x=\frac{1740}{29}=60\] \[\Rightarrow \] \[140\times 605=11\times L.C.M.\]