弧长为C=4π,弧所对的圆心角为A=60°,则所对的弦长L为多少?
弧半径为R.
A=60°=60°*π/180°=π/3弧度
R=C/A=4π/(π/3)=4π*(3/π)=12
L=2*R*SIN(A/2)
=2*12*SIN(60°/2)
=12