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A restaurant has a giant fish tank, shown at the right in the shape of an octagonal prism. Find the volume and surface area of the fish tank if the base is a regular octagon with the side length 0.6m and the height of the prism is 3m.

User Camion
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1 Answer

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Answer:

Explanation:

The octagonal prism is made up of 8 rectangular sides and 2 octagonal bases. We would determine the surface area by applying the formula,

Surface area = 2 × area of octagonal base + (number of sides × area of rectangular face)

Area of rectangular face = 0.6 × 3 = 1.8m²

To determine the area of the base, we would determine the length of the apotherm,a by applying the formula,

a = s/2tan(180/n)

n = number of sides = 8

s = length of each side

a = 0.6/2tan(180/8) = 0.6/2tan22.5

a = 0.72

Also,

a = 2A/p

Where

A = area of octagonal base

p = perimeter of octagonal base

p = number of sides × side length

p = 8 × 0.6 = 4.8m

Therefore,

0.72 = 2A/4.8

A = (0.72 × 4.8)/2 = 1.728m²

Therefore,

Surface area = (2 × 1.728) + (8 × 1.8)

Surface area = 17.856m²

The formula for determining the volume is

Volume = base area × height

Volume = 1.728 × 3 = 5.184m³

User Pantera
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