100.48÷2=3.14 × r × rr × r =16r=4S=3.14 × r × r × 2+2 × 3.14 × 4 × 90 =100.48+2260.8 =2361.28(平方厘米）如果有帮到您 请给予好评 谢谢拉#^_^#祝您愉快
