弧长C=5.11m 弦长L=4.8m 怎么算圆弧面积S?弧的半径为R,弧所对的圆心角为A.Rn+1=(1+(L-2*Rn*SIN(C/(2*Rn)))/(L-C*COS(C/(2*Rn))))*RnR0=4R1=4.175R2=4.196R3=4.196R=4.196A=2*ARC SIN((L/2)/R)=2*ARC SIN((4.8/2)/4.1...