一个圆柱，底面半径为2厘米，高为5厘米，它的底面积为______平方厘米，侧面积为______平方厘米，表面积为______平方厘米．体积为______立方厘米．
（1）圆柱的底面积：
3.14×22=12.56（平方厘米）；
（2）圆柱的侧面积：
3.14×2×2×5，
=12.56×5，
=62.8（平方厘米）；
（3）表面积是：
62.8+12.56×2，
=62.8+25.12，
=87.92（平方厘米）；
（3）12.56×5=62.8（立方厘米）；
答：它的底面积是12.56平方厘米，侧面积是62.8平方厘米，表面积是87.92平方厘米，体积是62.8立方厘米．
故答案为：12.56；62.8；87.92；62.8．
According to the Chinese Association on Tobacco Control, about 350 million Chinese smoke. Among them, 50 million are teenagers. Sun Jiangping of Beijing University said, “ Teenagers can get cigarettes 3 , especially when their parents smoke or shops sell cigarettes to them. It’s very important for parents to help their children 4 smoking.” A 15-year-old boy 5 Li Kun from Beijing said his parents didn’t smoke. Because they 6 smoking could make people feel 7 ill, they only 8 him to play with friends without smoking. 9 in such a good family helped Li say no to cigarettes. Some of his smoking classmates once told Li that smoking made boys look cool, but Li disagreed. He said, “Smoking is 10 and it’s not cool at all. Please stop smoking now!” |