已知拱高及弦长，求半径 知道弦长和拱高，怎么求半径？
\u77e5\u9053\u5f26\u957f\u548c\u62f1\u9ad8\uff0c\u600e\u4e48\u6c42\u534a\u5f84\uff0c\u516c\u5f0f\uff1a
\u5df2\u77e5\u5f26\u957fL\u548c\u62f1\u9ad8H\u6c42\u534a\u5f84R\u7684\u516c\u5f0f\uff1aR^2=(R-H)^2+(L/2)^2
2.\u89e3\u9898\u6b65\u9aa4\uff1a
R^2=(R-H)^2+(L/2)^2
R^2=R^2-2*H*R+H^2+L^2/4
2*H*R=H^2+L^2/4
R=H/2+L^2/(8*H)
3.\u4f8b\u98981\uff1a
\u5df2\u77e5\u5f26\u957f\u662f3295mm,\u62f1\u9ad8213mm,\u6c42\u534a\u5f84.
\u5f26\u957fL=3295mm,\u5f27\u9ad8H=213mm,\u6c42\u534a\u5f84R?R^2=(R-H)^2+(L/2)^2R^2=R^2-2*R*H+H^2+L^2/42*R*H=H^2+L^2/4R=H/2+L^2/(8*H)=213/2+3295^2/(8*213)=6477.99mm
\u4f8b\u98982\uff1a
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\u7b54\uff1a\u8bbe\u534a\u5f84\u4e3arr^2=(r-70)^2 + \uff08180/2\uff09^2
\u6b65\u9aa4\u7565\u3002\u4ee3\u5165\u89e3\u9898\u6b65\u9aa4\u5373\u53ef\u3002
4.\u5df2\u77e5\u5f26\u957f\uff0c\u62f1\u9ad8\uff0c\u6c42\u5f27\u957f\u3002
\u9898\uff1a\u5df2\u77e5\u5f26\u957f0.85\u7c73,\u62f1\u9ad80.4\u7c73,\u6c42\u5f27\u957f\u8ba1\u7b97\u516c\u5f0f
\u7b54\uff1a\u5f27\u534a\u5f84\u4e3aR,\u5f27\u6240\u5bf9\u7684\u5706\u5fc3\u89d2\u4e3aA.
R^2=(R-H)^2+(L/2)^2R^2=R^2-2*R*H+H^2+L^2/42*R*H=H^2+L^2/4R=H/2+L^2/(8*H)=0.4/2+0.85^2/(8*0.4)=0.426\u7c73
A=2*ARC SIN((L/2)/R)=2*ARC SIN((0.85/2)/0.426)=173.057\u5ea6=173.057*PI/180=3.02042\u5f27\u5ea6C=A*R=3.02042*0.426=1.286\u7c73
\u516c\u5f0f\uff1a
\u5df2\u77e5\u5f26\u957fL\u548c\u62f1\u9ad8H\u6c42\u534a\u5f84R\u7684\u516c\u5f0f\uff1aR^2=(R-H)^2+(L/2)^2
2.\u89e3\u9898\u6b65\u9aa4\uff1a
R^2=(R-H)^2+(L/2)^2
R^2=R^2-2*H*R+H^2+L^2/4
2*H*R=H^2+L^2/4
R=H/2+L^2/(8*H)
3.\u4f8b\u98981\uff1a
\u5df2\u77e5\u5f26\u957f\u662f3295mm,\u62f1\u9ad8213mm,\u6c42\u534a\u5f84.
\u5f26\u957fL=3295mm,\u5f27\u9ad8H=213mm,\u6c42\u534a\u5f84R?R^2=(R-H)^2+(L/2)^2R^2=R^2-2*R*H+H^2+L^2/42*R*H=H^2+L^2/4R=H/2+L^2/(8*H)=213/2+3295^2/(8*213)=6477.99mm
\u4f8b\u98982\uff1a
\u9898\uff1a\u5f26\u957f180,\u62f1\u9ad870 \uff0c\u6c42\u534a\u5f84\u7684\u516c\u5f0f\u3002
\u7b54\uff1a\u8bbe\u534a\u5f84\u4e3arr^2=(r-70)^2 + \uff08180/2\uff09^2
\u6b65\u9aa4\u7565\u3002\u4ee3\u5165\u89e3\u9898\u6b65\u9aa4\u5373\u53ef\u3002
4.\u5df2\u77e5\u5f26\u957f\uff0c\u62f1\u9ad8\uff0c\u6c42\u5f27\u957f\u3002
\u9898\uff1a\u5df2\u77e5\u5f26\u957f0.85\u7c73,\u62f1\u9ad80.4\u7c73,\u6c42\u5f27\u957f\u8ba1\u7b97\u516c\u5f0f
\u7b54\uff1a\u5f27\u534a\u5f84\u4e3aR,\u5f27\u6240\u5bf9\u7684\u5706\u5fc3\u89d2\u4e3aA.
R^2=(R-H)^2+(L/2)^2R^2=R^2-2*R*H+H^2+L^2/42*R*H=H^2+L^2/4R=H/2+L^2/(8*H)=0.4/2+0.85^2/(8*0.4)=0.426\u7c73
A=2*ARC SIN((L/2)/R)=2*ARC SIN((0.85/2)/0.426)=173.057\u5ea6=173.057*PI/180=3.02042\u5f27\u5ea6C=A*R=3.02042*0.426=1.286\u7c73
设半径为r
r²=(32÷2)²+(r-3)²
6r=256+9
r=265÷6
r≈44.17厘米
保留两位小数
补成一个扇形，再用勾股定理去求。
己知弧长为2米，拱高为382厘米求半径
已知拱高43弦长220求半径
你这样算简单一点：设拱高为h，弦长的一半为a，半径为r。那么r=（h²+a²）÷2h。所以结果就是：半径=（3²+16²）÷6
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绛旓細R=(3604²+4*346²)/8*346 =4865.49
