Half-cylinder 25121

How much sheet metal do we use to produce a gutter pipe in the shape of a hollow half-cylinder 20 m long and 16 cm wide if we count 8% for bending and welding?

Correct answer:

A =  5.4287 m²

Step-by-step explanation:

$$\begin{gathered} D=16\text{cm}\to \text{m}=16:100\text{m}=0.16\text{m} \\ r=D/2=0.16/2=\frac{2}{25}=0.08\text{m} \\ l=20\text{m} \\ {S}_1=\pi \cdot D\cdot l=3.1416\cdot 0.16\cdot 20\doteq 10.0531{\text{m}}^2 \\ q=100\%+8\%=1+\frac{8}{100}=1.08 \\ A=S_1/2\cdot q=10.0531/2\cdot 1.08=5.4287{\text{m}}^2 \end{gathered}$$

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