弧长计算公式 弦长L=30米,高H=1米,求弧长C是多少?
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)
=1/2+30^2/(8*1)
=113
A=2*ARC SIN((L/2)/R)
=2*ARC SIN((30/2)/113)
=15.256度
=15.256*PI/180
=0.26627弧度
C=A*R
=0.26627*113
=30.089米