若1rad的圆心角所对的弦长为2,则这圆心角所对的弧长为多少?

若1rad的圆心角A所对的弦长为L=2,则这圆心角所对的弧长C为多少?
弧半径为R.
A=1rad=1*180/PI=57.296度
R=(L/2)/SIN(A/2)
=(2/2)/SIN(57.296/2)
=2.086
C=A*R
=1*2.086
=2.086