已知一圆半径为R=2146mm　,圆上一弧长为C=609mm　,求该弧长所对应的弦长L是多少?
弧所对的圆心角为A.
A=C/R=609/2146=0.283784弧度=0.283784*180/PI=16.26度
L=2*R*SIN(A/2)
=2*2146*SIN(16.26/2)
=606.96mm