已知扇形半径为R=2000cm,弦长为L=243.7cm,如何计算弧长C?弧所对的圆心角为A.A=2*ARC SIN((L/2)/R)=2*ARC SIN((243.7/2)/2000)=6.99度=6.99*PI/180=0.121926弧度C=R*A=2000*0.121926=243.851cm...