The hollow cylinder

The hollow cylinder has a height of 70 cm, an outer diameter of 180 cm, and an inner diameter of 120 cm. What is the body's surface, including the area inside the cavity?

Final Answer:

S =  94247.7796 cm²

Step-by-step explanation:

$$\begin{gathered} h=70\text{cm} \\ {D}_1=180\text{cm} \\ {D}_2=120\text{cm} \\ {o}_1=\pi \cdot D_1=3.1416\cdot 180\doteq 565.4867\text{cm} \\ {o}_2=\pi \cdot D_2=3.1416\cdot 120\doteq 376.9911\text{cm} \\ {S}_1=\pi \cdot (D_1/2{)}^2=3.1416\cdot (180/2{)}^2\doteq 25446.9005{\text{cm}}^2 \\ {S}_2=\pi \cdot (D_2/2{)}^2=3.1416\cdot (120/2{)}^2\doteq 11309.7336{\text{cm}}^2 \\ M=2\cdot (S_1-S_2)=2\cdot (25446.9005-11309.7336)\doteq 28274.3339{\text{cm}}^2 \\ S=M+o_1\cdot h+o_2\cdot h=28274.3339+565.4867\cdot 70+376.9911\cdot 70=94247.7796{\text{cm}}^2 \end{gathered}$$

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