弧半徑為R,弧所對的圓心角為A.
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)
=0.8/2+1^2/(8*0.8)
=0.55625m
A=2*ARC SIN((L/2)/R)
=2*ARC SIN((1/2)/0.55625)
=128.022度
C=PI*R*A/180=PI*0.55625*128.022/180=1.243m
弦長L=3.76m弦高H=1.14m,求弧長C?
弧半徑為R,弧所對的圓心角為A.
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)
=1.14/2+3.76^2/(8*1.14)
=2.12m
A=2*ARC SIN((L/2)/R)
=2*ARC SIN((3.76/2)/2.12)
=124.928度
C=PI*R*A/180=PI*2.12*124.928/180=4.623m若R>H，則：C=PI*R*A/180若R