弦长L=4.3米 弧高H=1.05米,怎样计算弧长C?
弧半径为R,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)
=1.05/2+4.3^2/(8*1.05)
=2.726米
A=2*ARC SIN((L/2)/R)
=2*ARC SIN((4.3/2)/2.726)
=104.12度
=104.12*PI/180
=1.8172弧度
C=A*R
=1.8172*2.726
=4.954米