知半径弧长算弦长.半径12.4,弧长6.991.
问题描述：
知半径弧长算弦长.
半径12.4,弧长6.991.
答
知半径R=12.4弧长C=6.991算弦长L?
弧所对的圆心角为A.
A=C/R=6.991/12.4=0.56379弧度=0.56379*180/PI=32.3度
L=2*R*SIN(A/2)
=2*12.4*SIN(32.3/2)
=6.899