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【例1】一个无盖的圆柱形铁皮水桶,高是30厘米,底面直径是20厘米,做这个水桶要用铁皮多少平方厘米?(得数保留整百平方厘米)【错解】(1)水桶的侧面积:3.14 20 30=1884(平方厘米)(2)水桶的底面积:3.14(202)2=314(平方厘米)(3)需要铁皮:1884+314 2=2512≈2600(平方厘米)
【Example 1】 A lidless cylindrical metal buckets, height is 30 cm, the bottom diameter is 20 cm, how many square centimeters do you want to use this bucket? (Remaining hundreds of square centimeters) [wrong solution] (1) The side area of the bucket: 3.14 20 30 = 1884 (cm 2) (2) The area of the bottom of the bucket: 3.14 (202) 2 = 314 (cm 2) (3) Requires tin: 1884 + 314 2 = 2512≈2600 )