已知弦长L=1480,弓高H=30 求半径R和弧长C?
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)
=30/2+1480^2/(8*30)
=9141.67
A=2*ARC SIN((L/2)/R)
=2*ARC SIN((1480/2)/9141.67)
=9.286度
C=PI*R*A/180=PI*9141.67*9.286/180=1481.62
已知弦长L=1480,弓高H=30 求半径R和弧长C?
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)
=30/2+1480^2/(8*30)
=9141.67
A=2*ARC SIN((L/2)/R)
=2*ARC SIN((1480/2)/9141.67)
=9.286度
C=PI*R*A/180=PI*9141.67*9.286/180=1481.62