The listing, for anybody that wants to try it:

`10 REM graphics by Salim Benadel`

15 RANDOMIZE TIME

20 DEFINT b,c,x:DEFREAL d,e,f

30 MODE 2

40 b=RND*5+1:c=RND*5+1

50 ORIGIN 320,200

55 d=100*COS(1):e=200*COS(1/b):f=200*SIN(1/c)

60 FOR a=2 TO 1000 STEP PI/30

70 x=100*COS(a):MOVE x,x

80 DRAW 200*COS(a/b),200*SIN(a/c)

90 IF INT(d/20)=INT(5/COS(a)) AND INT(e/20)=INT(10*COS(a/b)) AND INT(f/20)=INT(10*SIN(a/c)) THEN 110

100 NEXT a:GOTO 30

110 FOR z=a TO a+20 STEP PI/30

120 x=100*COS(a):MOVE x,x

130 DRAW 200*COS(z/b),200*SIN(z/c)

140 NEXT z:GOTO 30