Wooden container

The locksmith should cover the cube-shaped wooden container with a metal sheet inside. The outer edge of the container is 54cm. The wall thickness is 25 mm. The container has no lid. Calculate. How many sheets will be needed to cover it?

Correct answer:

S =  12495 cm²

Step-by-step explanation:

$$\begin{gathered} a=54\text{cm} \\ h=25\text{mm}\to \text{cm}=25:10\text{cm}=2.5\text{cm} \\ b=a-2\cdot h=54-2\cdot 2.5=49\text{cm} \\ c=a-h=54-2.5=\frac{103}{2}=51.5\text{cm} \\ S=4\cdot b\cdot c+b^2=4\cdot 49\cdot 51.5+49^2=12495{\text{cm}}^2 \end{gathered}$$

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