Make 1 section of the same cylindrical ventilation pipe, the diameter of the bottom surface of the ventilation pipe is 20 cm, and the length is 1.2 meters. How many square meters of iron sheet is needed to make this ventilation pipe?
做1节相同的圆柱形通风管，通风管的底面直径是20厘米，长1.2米．做这个通风管至少需要多少平方米铁皮？
<result>0.756</result>