已知圆弧弦AC长L=7.6米,拱BO高H=4.6米,求弧度、弧长C、圆心角A、圆半径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)
=4.6/2+7.6^2/(8*4.6)
=3.87米
A=2*ARC SIN((L/2)/R)
=2*ARC SIN((7.6/2)/3.87)
=158.24度
=158.24*PI/180
=2.761786弧度
C=R*A=3.87*2.761786=10.687米