The figure is a square based pyramid. Total surface area of the pyramid is 9072m³. If the length of the side of the square base is 56 cm , find the volume of the pyramid.

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Respuesta :

msm555

The volume of the pyramid=47040[tex]m^3[/tex]

Answer:

Solution Given:

The total surface area of the pyramid = [tex]9072\:m^2[/tex]

let the height be AB be h.

length of side[l]=56 m

The volume of the pyramid=?

let slant height be AC=a.

and BC=b

we have,

The perimeter of base[P]=4l=4*56=224m

BC=28m

Now;

The total surface area of the pyramid = [tex]9072\:m^2[/tex]

lateral= surface area +base area=[tex]9072\:m^2[/tex]

[tex]\frac{1}{2}*P*a+l^2=9072\:m^2[/tex]

[tex]\frac{1}{2}*224*a+56^2=9072\:m^2[/tex]

[tex]112a=9072-3136[/tex]

[tex]a=\frac{5936}{112}=53m[/tex]

now

By using Pythagoras law;

[tex]AC^2=AB^2+BC^2[/tex]

[tex]a^2=h^2+b^2[/tex]

[tex]53^2=h^2+28^2[/tex]

[tex]h^2=2809-784[/tex]

[tex]h=\sqrt{2025}[/tex]

h=45m

now,

The volume  of the pyramid=[tex]\frac{1}{3}*l^2*h[/tex]

[tex]\frac{1}{3}*56^2*45=47040m^3[/tex]

Step-by-step explanation:

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