若1弧度的圆心角,所对的弦长等于2,则这圆心角所对的弧长等于多少 要详细过程 谢谢··

若A=1弧度的圆心角,所对的弦长L=2,则这圆心角所对的弧长C等于多少?
设圆半径为R
SIN(A/2)=(L/2)/R
R=(L/2)/(SIN(A/2))
=(2/2)/(SIN(1/2))
=1/(SIN((180/PI)*1/2))
=1/SIN(28.6479)
=2.086
C=A*R
=1*2.086
=2.086