枫林小区里有一个半径是20.5m的植草的圆形花圃,花圃外围是一圈宽50cm的环形花台,
1个回答

1)花圃周长= π×d

= π×20.5×2

= 41π

≈128.74(m)

128.74÷1.5 ≈85.8

答:至少可以摆85盆花

2)花圃面积= π×r×r

= π×20.5×20.5

= 420.25π

≈1319.59(m²)

1319.59×2=2639.17(元)

答:植完整个草坪需要2639.17元

3)花台面积= π×R×R - π×r×r

= π×(20.5+0.5)×(20.5+0.5)- π×20.5×20.5

= π×21×21 - π×20.5×20.5

= 441π - 420.25π

= 20.75π

≈65.155(m²)

65.155×8≈521.2≈522(块)

答:贴完花台至少需要522块瓷砖