10 CLS 3
20 SCREEN 3
30 PI=3.1415927#
40 X0=320
50 Y0=200
60 INPUT "Šî‘b‰~”¼Œa‚Í";RB
70 A=PI/180
80 LINE(X0-200,Y0)-(X0+200,Y0)
90 LINE(X0,Y0-100)-(X0,Y0+100)
100 FOR J=1 TO 985
110 A1=-J*A:A2=-(J+1)*A
120          CIRCLE(320,200),RB
130          XM11=RB*COS(A1)+RB*A1*SIN(A1):XM12=RB*COS(A2)+RB*A2*SIN(A2)
140          YM11=RB*SIN(A1)-RB*A1*COS(A1):YM12=RB*SIN(A2)-RB*A2*COS(A2)
150          LINE(XM11+320,YM11+200)-(XM12+320,YM12+200),7
160 NEXT J
170 FOR U=1 TO 985 
180          O1=-U*A:O2=-(U+1)*A
190          XM11=RB*COS(O1+PI)+RB*O1*SIN(O1+PI):XM12=RB*COS(O2+PI)+RB*O2*SIN(O2+PI)
200          YM11=RB*SIN(O1+PI)-RB*O1*COS(O1+PI):YM12=RB*SIN(O2+PI)-RB*O2*COS(O2+PI)
210          LINE(XM11+320,YM11+200)-(XM12+320,YM12+200),4
220 NEXT U
230 END