rrrr底底高高长长宽宽长方形面积长方形面积=×=×平行四边形面积平行四边形面积=×=×长长底底宽宽高高171819202122232425262728293031324235678910111213141516142356789101112131415161423567891011121314151611718192021222324252627282930313217181920212223242526272829303132123456789101112131415163231302928272625242322212019181712345678910111213141516123456789101112131415161234567891011121314151612345678910111213141516123456789101112131415161234567891011121314151612345678910111213141516123456789101112131415161234567891011121314151612345678910111213141516C÷2r宽长rrrrS=S=22rr一个圆的半径是4厘米,它的面积是多少平方厘米？3.14×42=50.24(平方厘米)答：它的面积是50.24平方厘米。
