设弓形弦长为L,弓形高为H,弧的圆心角为A,弧半径为R,弧长为C。若已知弦长为L,弓形高为H。则: R=(L^2+4*H^2)/(8*H) A=2*ARC SIN(L/(2*R))度 =2*(ARC SIN(L/(2*R)))*PI/180 =(ARC SIN(L/(2*R)))*PI/90弧度 C=R*A(弧度) =R*(ARC SIN(L/(2*R)))*PI/90