公园里有一个圆形花坛,直径是16m,在它的周围修建一条2m宽的环形便道。(圆周率取值为3)
\u516c\u56ed\u6709\u4e00\u4e2a\u5706\u5f62\u82b1\u575b\uff0c\u76f4\u5f84\u662f16m\uff0c\u5728\u5b83\u7684\u5468\u56f4\u4fee\u5efa\u4e00\u67612m\u5bbd\u7684\u73af\u5f62\u4fbf\u9053\u3002\uff08\u5706\u5468\u7387\u53d6\u503c\u4e3a3\uff09 \uff081\uff09\u8fd9\u5c0f\u5706\u534a\u5f84=\u82b1\u575b\u534a\u5f84 16\u00f72=8\uff08\u7c73\uff09
\u5927\u5706\u534a\u5f848+2=10\uff08\u7c73\uff09
\u73af\u5f62\u9762\u79ef\uff1a3.14\u00d7\uff0810²-8²\uff09
=3.14\u00d736
=113.04\uff08\u5e73\u65b9\u7c73\uff09
\uff082\uff09 \u5468\u957f 3.14\u00d710\u00d72=62.8\uff08\u7c73\uff09
62.8\u00f75\u224812\uff08\u76cf\uff09
(1)\u9762\u79ef=3*10*10-3*8*8=108\u5e73\u65b9\u7c73
\uff082\uff09\uff083*(16+4)/5}-1=11\u76cf (12-1)
1。用两个圆的面积差来做。大圆面积为3x(8+2)^2=300,小圆面积为3x8^2=192,则便道面积300-192=108平方米2.就是求外圆的周长啦,为2x3x(8+2)=60m,所以要装60/5=12盏灯
(1)3X10X10-3X8X8=108(平方米)(2)3X20=600(米) 600÷5=120(盏)
绛旓細瑙o細锛1锛夌幆褰究閬撶殑鍐呭渾鍗婂緞鏄細16梅2=8(m)鐜舰渚块亾鐨勫鍦嗗崐寰勬槸锛8+2=10(m)杩欐潯渚块亾鐨勯潰绉槸:3X10X10-3X8X8=108(骞虫柟绫筹級锛2锛夌幆褰究閬撶殑澶鍦嗙殑鍛ㄩ暱鏄細2X3X10=60(m)瑕佸畨瑁呯伅:60梅5=12(鐩)绛旓細銆傘傘
绛旓細鍥犱负鑺卞潧鐨鐩村緞涓12绫筹紝鍒欏叾鍗婂緞涓12梅2=6绫=600鍘樼背锛屼簬鏄彲浠ラ夋嫨1锛300鐨勬瘮渚嬪昂锛涘洜姝よ姳鍧涘崐寰勭殑鍥句笂璺濈鏄細600脳1300=2锛堝帢绫筹級锛屼粠鑰岀敾鍥惧涓嬶細锛
绛旓細鍥炵瓟锛18梅0.4=45
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绛旓細18梅2=9锛堢背锛9+1=10锛堢背锛3.14脳锛10 2 -9 2 锛=3.14脳19锛=59.66锛堝钩鏂圭背锛夌瓟锛氳繖鏉$煶瀛愯矾鐨勯潰绉槸59.66骞虫柟绫筹紟
绛旓細16梅2=8绫 8+2=10绫 鐜板湪鑺卞渻鐨勯潰绉槸锛3.14脳10²-3.14脳8²=314-200.96 =113.04骞虫柟绫
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