知道弦长L=1.6m,弧高H=0.65,怎么求弧长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*H*R+H^2+L^2/4
2*H*R=H^2+L^2/4
R=H/2+L^2/(8*H)
=0.65/2+1.6^2/(8*0.65)
=0.8173m
A=2*ARC SIN((L/2)/R)
=2*ARC SIN((1.6/2)/0.8173)
=156.375度
C=PI*R*A/180=PI*0.8173*156.375/180=2.231m