弓形底线L=1930高H=340,求这个弓形角度A的度数和弧长C多少?
弧半径为R.
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)
=340/2+1930^2/(8*340)
=1539.449
A=2*ARC SIN((L/2)/R)
=2*ARC SIN((1930/2)/1539.449)
=77.636度
=77.636*PI/180
=1.355002弧度
C=R*A=1539.449*1.355002=2085.96