设扇形S1=(N1/360)*3.14*R1^2, S2=(N2/360)*3.14*R2^2 S1/S2=(N1*R1^2)/(N2*R2^2)=1/2 N1/N2=2/1, 则有R1^2/R2^2=1/4 即有R1/R2=1/2 N1是扇形S1的圆心角,N2是扇形S2的圆心角,R1、R2分别为半径
