L=3.098,H=0.34,求这个弓形的面积S?
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*R*H+H^2+L^2/4
2*R*H=H^2+L^2/4
R=H/2+L^2/(8*H)
=0.34/2+3.098^2/(8*0.34)
=3.699米
A=2*ARC SIN((L/2)/R)
=2*ARC SIN((3.098/2)/3.699)
=49.52度
S=PI*R^2*A/360-(L/2)*R*COS(A/2)
=PI*3.699^2*49.52/360-(3.098/2)*3.699*COS(49.52/2)
=0.708平方米