已知弦长L=16米,拱高H=2米,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)
=2/2+16^2/(8*2)
=17米
A=2*ARC SIN((L/2)/R)
=2*ARC SIN((16/2)/17)
=56.145度
=56.145*PI/180
=0.979915弧度
C=R*A=17*0.979915=16.659米