弦长38.75米,弧垂0.943米,求弧长.弦长21米,弧垂0.829米,求弧长.

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弦长38.75米,弧垂0.943米,求弧长.弦长21米,弧垂0.829米,求弧长.
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弦长38.75米,弧垂0.943米,求弧长.弦长21米,弧垂0.829米,求弧长.
弦长38.75米,弧垂0.943米,求弧长.弦长21米,弧垂0.829米,求弧长.

弦长38.75米,弧垂0.943米,求弧长.弦长21米,弧垂0.829米,求弧长.
弦长L=38.75米,弧垂H=0.943米,求弧长C?
弧半径为R,弧所对的圆心角为A.
R^2=(R-H)^2+(L/2)^2
R^2=R^2-2*R*H+H^2+L^2/4
2*R*H=H^2+L^2/4
R=H/2+L^2/(8*H)
=0.943/2+38.75^2/(8*0.943)
=199.512米
A=2*ARC SIN((L/2)/R)
=2*ARC SIN((38.75/2)/199.512)
=11.15度
=11.15*PI/180
=0.19453弧度
C=R*A=199.512*0.19453=38.811米
弦长L=21米,弧垂H=0.829米,求弧长C?
弧半径为R,弧所对的圆心角为A.
R^2=(R-H)^2+(L/2)^2
R^2=R^2-2*R*H+H^2+L^2/4
2*R*H=H^2+L^2/4
R=H/2+L^2/(8*H)
=0.829/2+21^2/(8*0.829)
=66.91米
A=2*ARC SIN((L/2)/R)
=2*ARC SIN((21/2)/66.91)
=18.06度
=18.06*PI/180
=0.315156弧度
C=R*A=66.91*0.315456=21.087米