设扇形弧长为l,圆半径为r,
则l*r/2=31.4
π*r*r=157
r*r=157/3.14=50
圆心角=360*l/(2π*r)
=360*(2*31.4/r)/(2π*r)
=360*31.4/(3.14*r*r)
=360*31.4/(3.14*50)
=72度
设扇形弧长为l,圆半径为r,
则l*r/2=31.4
π*r*r=157
r*r=157/3.14=50
圆心角=360*l/(2π*r)
=360*(2*31.4/r)/(2π*r)
=360*31.4/(3.14*r*r)
=360*31.4/(3.14*50)
=72度