两道关于圆的数学题，小学六年级的。 小学六年级五星题长方形两个圆求阴影面积
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S\u53f3\u4e0a\u9634\u5f71=S\u25b3ABC-S\u7ea2\u8272\u5757=S\u25b3ABC-\uff08S\u6247\u5f62OBC-S\u25b3OBC\uff09
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\u7b80\u5355\u8ba1\u7b97\u5f97AC=\u221a5\uff0cBC=2\u221a5.\uff08\u2220ACB\u662f\u76f4\u89d2\uff09
tan\u03b1=\u221a5/\uff082\u221a5\uff09=0.5\uff0c\u03b1\uff1darctan0.5
S\u6247\u5f62OBC=\u03c0\u00d75²\u00d7\uff082\u03b1/2\u03c0\uff09=25\u03b1
S\u25b3OBC=2\u221a5\u00d72\u221a5\u00f72=10
S\u25b3ABC=\u221a5\u00d72\u221a5\u00f72=5
\u6240\u4ee5\uff0cS\u9634\u5f71ABC=5-\uff0825\u03b1-10\uff09=15-25\u03b1=15-25arctan0.5
S\u9634\u5f71=\uff0810\u00d710-\u03c0\u00d75²\uff09\u00d7\uff083/4\uff09+S\u9634\u5f71ABC
S\u9634\u5f71=75-75\u03c0/4+15-25arctan0.5
S\u9634\u5f71=90-75\u03c0/4-25arctan0.5\uff08cm\uff09
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90-75*\u03c04-25*arctan(0.5) = 19.50394752017124
2X3.14X4/4+2X4=6.28+8=14.28
2、直径为6的半圆+正方形的三条边
2X3.14X(6/2)/2+3X6=9.42+18=27.42
1) 3.14×4×2×1/4+4×2
=6.28+8
=14.28cm
2)3.14×6×1/2+×6×3
=9.42+18
=27.42cm
1、1/4圆的周长+2倍半径
1/4π×4×2+2×4=14.28cm
2、1/2圆周长+3条边
1/2π×6+3×6=27.42cm
上面一题的答案是：
1/4×2×3.14×4=6.28（cm)
4+4+6.28=14.28（cm)
下面一题的答案是：
6×3=18（cm）
1/2×3.14×6=9.42（cm)
18+9.42=27.42(cm)
3.14×4×2×1/4+4×2
=6.28+8
=14.28cm
绛旓細1銆佸渾鍛ㄧ殑鍥涘垎涔嬩竴+浜涓崐寰 2X3.14X4/4+2X4=6.28+8=14.28 2銆佺洿寰勪负6鐨勫崐鍦+姝ｆ柟褰㈢殑涓夋潯杈 2X3.14X(6/2)/2+3X6=9.42+18=27.42
绛旓細1銆佸崐寰勫钩鏂规槸锛56.52脳2梅3.14=36 鎵浠ュ崐寰勬槸6鍘樼背 鍛ㄩ暱锛3.14脳6+6脳2=30.84鍘樼背 2銆佸崐寰勶細15.42梅锛3.14+2锛=3鍘樼背 闈㈢Н锛3.14脳3²梅2=14.13骞虫柟鍘樼背
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绛旓細1.鍦嗙洿寰:6绫.鍦嗛潰绉:3.14*3骞虫柟=28.26骞虫柟绫 鍓╀笅闈㈢Н:8*6-28.26=19.74骞虫柟绫 绛:鏉滈箖鑺卞崰28.26骞虫柟绫,鑼夎帀鑺卞崰19.74骞虫柟绫.2.璁惧叡鏈夐浂浠禭涓.鍒欑涓澶╁畬鎴怷/3涓 X/3+15=X/2 X=90 绛:鍏辨湁闆朵欢90涓
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绛旓細绗鍏锛氳繖棰樺氨鏄憡璇変綘鍦嗙殑鍛ㄩ暱锛岃浣犳眰鍦嗙殑闈㈢Н锛屾牴鎹懆闀=2蟺r锛屾眰鍑哄崐寰剅=L/2蟺=1.57/(2*3.14)=0.25锛岄偅涔堝渾鐨勯潰绉疭=蟺r²=3.14*0.25²=0.19625骞虫柟绫筹紝淇濈暀涓や綅灏忔暟灏辨槸0.20骞虫柟绫 鏈鍚庢垜鎯冲憡璇変綘锛岃繖鍑犻閮芥槸鍏充簬鍦嗙殑杩愮畻锛屽叾瀹炲渾鐨勮繍绠楀氨涓や釜鍏紡锛屽懆闀縇=2蟺...
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绛旓細1銆乺=6cm 鍗婂渾S=(6/2)鐨勫钩鏂逛箻浠ハ = 4.5 蟺 2銆乺=8cm 鍗婂渾S=(8/2)鐨勫钩鏂逛箻浠ハ = 8 蟺 3銆佷袱涓皬鍗婂渾S=4.5 蟺 + 8 蟺 = 12.5 蟺 4銆丷=10cm 鍗婂渾S=(10/2)鐨勫钩鏂逛箻浠ハ = 12.5 蟺 5銆佸嵆 涓や釜灏鍗鍦嗙殑S=澶у崐鍦嗙殑S銆
