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an eagle is flying at a constant height of 1000root3 meters from the ground level . a boy standing on the ground observes the angle of elevation of the eagles as 45. after 15 seconds it's angle becomes 30. find it's speed in km/hr

Respuesta :

Answer: [tex]240\sqrt{3}km/h[/tex]


Step-by-step explanation:

Let AB denote the height of eagle and and after 15 seconds it will become DE.

Also denote C is the point where boy is standing.

Now since both the triangles ABC and DEC are right angle triangle.

Now, in triangle ABC,

[tex]\tan45^{\circ}=\frac{AB}{BC}\\\Rightarrow1=\frac{1000\sqrt{3}}{BC}\\\Rightarrow\ BC=1000\sqrt{3}[/tex]

In triangle DEC,

[tex]\tan30^{\circ}=\frac{DE}{EC}\\\Rightarrow\frac{1}{\sqrt{3}}=\frac{1000\sqrt{3}}{EC}\\\Rightarrow\ EC=3\times1000\\\Rightarrow\ EC=3000[/tex]

Now, EB= [tex]3000-1000\sqrt{3}=1000(3-\sqrt{3})[/tex]

Speed of eagle =[tex]=\frac{EB}{time}=\frac{1000\sqrt{3}}{15}[/tex]

In km/hr

Speed of eagle =[tex]\frac{1000\sqrt{3}}{15}\times\frac{3600}{1000}=240\sqrt{3}km/h[/tex]

Ver imagen JeanaShupp