一条弦长L等于半径R的1/2,这条弦所对的圆心角A为几多弧度?
L=R/2
A=2*ARC SIN((L/2)/R)
=2*ARC SIN(((R/2)/2)/R)
=2*ARC SIN(1/4)
=28.955度
=28.955*PI/180
=0.5053605弧度