Respuesta :
As shown in the figure
Height of helicopter above the ground=30 m
Distance from the base to the point where the person is standing=30 m
height of the person=2 m
Now the person cast the shadow of length x m.
Triangle ABC and triangle EDC are similar.
∵ ∠B= ∠D=90°
∠C is common.
So by AA similarity ΔABC and ΔEDC are similar.
As we know when triangles are similar their sides are proportional.
AB/AD =BC/DC
Let DC=x meter
⇒[tex]\frac{10}{x}=\frac{30+x}{x}[/tex]
⇒5=\frac{30+x}{x}[/tex]
⇒5x=30+x
⇒4x = 30
⇒ x=30/4
⇒ x=7.5 meter
So length of shadow=7.5 meter
2. volume of a sphere of radius r is v (r) =[tex]\frac{4}{3}π r^{3}[/tex]
[tex]\frac{\mathrm{d} }{\mathrm{d} r}V[/tex]=4/3π×3[tex]r^2[/tex]
=4π[tex]r^2[/tex]
surface area of a sphere of radius r is 4π[tex]r^2[/tex]
b) Ratio of derivative of volume of sphere to surface area of sphere=[tex]\frac{4\pi r^2}{4\pi r^2}[/tex]
=1 [ incomplete question but you have written few words ]
