星期天,我和好朋友杨颖一起做数学家庭作业,眼看快要做完了,没想到却遇到了一只“拦路虎”:把一个圆柱沿着底面直径切成相等的两半,表面积增加了180平方厘米,原来这个圆柱的侧面积是多少平方厘米?杨颖说:“要求圆柱的侧面积,必须要知道它的底面周长和高,可是这两个条件现在一个都没有!” On Sunday, I was doing my math homework with my good friend Yang Ying. I was almost done, but I did not expect to encounter a “stumbling block”: cut a cylinder into two equal halves along the diameter of the bottom surface, and increased the surface area by 180 Square centimeter, the original side of the cylinder is the number of square centimeters? Yang Ying said: “The cylindrical side of the area, we must know its bottom circumference and height, but these two conditions are not one! ”