有两块半圆形的草坪，它们的周长都是128.5m，这两块草坪总面积是多少？详细讲解。 街心公园有两块半圆形的草坪，它们的周长都是128.5米，这两...
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128.5\u00f7\uff083.14+2\uff09\uff082\u03c0r/2+2r=128.5\uff0cr\u4e3a\u534a\u5f84\uff09
=128.5\u00f75.14
=25\u7c73
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3.14\u00d725²
=3.14\u00d7625
=1962.5\u5e73\u65b9\u7c73
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2个半圆相加的值是周长加4个半径，通过相等关系即可求得
解: 因为它们的周长=2兀R=128.5，所以R=128.5/2兀
面积=兀R²=兀（128.5/2兀）² ≈ 2629.34 m³
128.5除3.14除2
半径：128.5÷（3.14+2）=25米
圆周长的一半=圆周率×半径
直径=半径×2
因为半圆周长=圆周长的一半+直径
则半圆周长=圆周长的一半+直径=(圆周率+2)×半径
半圆面积：3.14×25²÷2=981.25平方米
两块草坪面积=981.25*2=1962.5平方米
绛旓細濡傚彸鍥撅紝琛楀績鍏洯鏈変袱鍧楀崐鍥舰鐨勮崏鍧紝瀹冧滑鐨勫懆闀块兘鏄128.5m锛岃繖涓ゅ潡鑽夊潽鐨勬婚潰绉槸澶氬皯锛熻В锛氳鍦嗗舰鑽夊潽鐨勭洿寰勬槸d绫筹紝3.14脳d梅2+d=128.5 2.57d=128.5 d=50 闈㈢Н涓猴細3.14脳锛50梅2锛²=3.14脳625 =1962.5锛堝钩鏂圭背锛夌瓟锛氳繖鍧楄崏鍧殑鎬婚潰绉槸1962.5骞虫柟绫锛
绛旓細鍥犳鍗婂渾褰㈢殑鍛ㄩ暱涓猴細2鈭弐/2 + 2r= 鈭弐 + 2r 鑰岀敱棰樻剰鐭ヤ簩鍧楀崐鍦嗗舰鐨勮崏鍧紝瀹冧滑鐨勫懆闀跨浉绛 鍥犳鍙煡锛氫粬浠殑鍗婂緞涔熺浉绛夛紝鍗冲畠浠槸涓や釜瀹屽叏涓鏍风殑鍗婂渾 瀹冧滑鐨勬婚潰绉嵆涓轰竴涓暣鍦嗙殑闈㈢Н锛屼篃灏辨槸S= 鈭弐^2 (涔熷氨鏄垙r鐨勫钩鏂圭殑鎰忔)鐢憋細鈭弐 + 2r= 3.14r + 2r=5.14r = 128.5 ...
绛旓細琛楀績鍏洯鏈変袱鍧楀崐鍦嗗舰鐨勮崏鍧,瀹冧滑鐨勫懆闀块兘鏄128.5绫,杩欎袱鍧楄崏鍧殑鎬婚潰绉槸澶氬皯锛熷崐寰128.5梅锛3.14+2锛=128.5梅5.14 =25绫 闈㈢Н3.14脳25²=3.14脳625 =1962.5骞虫柟绫 甯屾湜瀵逛綘鏈夋墍甯姪 杩樻湜閲囩撼~~
绛旓細瑙ｏ細鍥犱负鍗婂渾鐨勫懆闀=蟺r+2r 鍗筹細蟺r+2r=128.5 锛3.14+2锛塺=128.5 5.14 r=128.5 r=25 涓ゅ潡鑽夊潽鐨勯潰绉細3.14脳25²=1962.5骞虫柟绫
绛旓細绛旓細鍗婂渾鍗婂緞涓篟锛屽垯鍗婂渾寮ч暱=蟺R 鍒欏崐鍦嗗懆闀=2R+蟺R=(2+蟺)R 涓や釜鍗婂渾鐨勫懆闀跨浉绛変负128.5锛屽垯鍗婂緞鐩哥瓑 鎵浠ワ細(2+蟺)R=128.5 R=25绫 涓や釜鐩稿悓鍗婂緞鐨勫崐鍦嗗彲浠ユ嫾鎴愪竴涓渾 鎵浠ワ細闈㈢НS=蟺R^2=625蟺=1962.5骞虫柟绫 鎵浠ワ細鎬婚潰绉负1962.5骞虫柟绫 ...
绛旓細瑙ｏ細鏍规嵁棰樻剰鍙煡锛氫袱涓崐鍦嗗舰鑽夊潽鐨勫崐寰=128.5梅锛3.14+2锛=25锛堢背锛夛紱鍒欐婚潰绉负25脳25脳3.14=1962.5锛堝钩鏂圭背锛夈傜瓟锛杩欎袱鍧楄崏鍧殑鎬婚潰绉摝1962.5骞虫柟绫銆
绛旓細鍏洯鏈変袱鍧楀崐鍦嗗舰鐨勮崏鍧紝浠栦滑鐨勫懆闀块兘鏄128.5绫锛岃繖涓ゅ潡鑽夊潽鐨勬婚潰绉槸澶氬皯锛熻锛氳繖涓ゅ潡鑽夊潽鐨勫崐寰勪负R 2R蟺+4R=128.5锛岋紝R=12.5 杩欎袱鍧楄崏鍧殑闈㈢Н鍜=R²蟺=490.625锛堝钩鏂圭背锛
绛旓細鍗婂緞寰堝ソ姹 寰楀埌鍗婂緞涓25鍚庯紝闈㈢Н灏辨槸1962.5骞虫柟绫 2涓崐鍦嗙浉鍔犵殑鍊兼槸鍛ㄩ暱鍔4涓崐寰勶紝閫氳繃鐩哥瓑鍏崇郴鍗冲彲姹傚緱
绛旓細鏈夐鎰忓彲鐭ワ紝涓ゅ潡鑽夊潽鏄袱涓崐鍦锛屽畠浠鍚堣捣鏉ュ氨鏄竴鏁翠釜鍦嗙殑闈㈢Н銆傚亣璁惧崐鍦嗙殑鍗婂緞涓簉 鍗婂渾鐨勫懆闀涓猴細2r+蟺r=128.5 锛坢锛夊彇蟺=3.14 姹傚緱锛歳=25锛坢锛変袱鍧楄崏鍧殑鎬婚潰绉 S=蟺r²=3.14*25²=1962.5锛坢²锛
绛旓細璁惧渾褰㈣崏鍧殑鐩村緞鏄痙绫筹紝3.14脳d梅2+d=128.5 2.57d=128.5 d=50 闈㈢Н涓猴細3.14脳锛50梅2锛2 =3.14脳625 =1962.5锛堝钩鏂圭背锛夌瓟锛杩欏潡鑽夊潽鐨勬婚潰绉槸1962.5骞虫柟绫銆
