10 E=90:S=2
20 HH=400:BB=100:V=100:R=SQR 3/2:VV=1.5*V:V=V/2
22 OX=500:OY=1:X1=OX:Y1=OY:X2=OX:Y2=OY+HH:H=Y2-Y1:OC=5
25 GRAPH :LLINE (0,0)-(0,-HH),9,0:SORGN 
30 FF=1
35 FOR RR=0TO 2
40 I=0:T=0
45 PRINT "R=";RR*120
50 X=X2:Y=Y2:GOSUB 500:XR=X:YR=Y
150 F=FF
170 FOR N=0TO ESTEP S
180 PRINT T;
190 T5=T*5
200 CY=OC+Y2/2*ABS SIN T:DY=CY
210 CX=OX-V-ABS (VV*SIN T5)
220 DX=OX+V+ABS (VV*SIN (T5+120))
230 X=CX:Y=CY:GOSUB 500:CX=X:CY=Y
240 X=DX:Y=DY:GOSUB 500:DX=X:DY=Y
250 IF I=0GOSUB 280ELSE GOSUB 290
260 T=T+S:NEXT N
265 FF=FF+1:PRINT :NEXT RR
270 END 
280 CALL &C0C5;(X1,Y1,CX,CY)-(DX,DY,XR,YR),0,F:I=1:RETURN 
290 CALL &C0C5;(XR,YR,DX,DY)-(CX,CY,X1,Y1),0,F:I=0:RETURN 
300 LLINE (X-5,Y-5)-(X+5,Y+5),0,F
310 LLINE (X-5,Y+5)-(X+5,Y-5),0,F
320 RETURN 
330 GRAPH 
340 F=2:X=X1:Y=Y1:GOSUB 300
350 F=1:X=CX:Y=CY:GOSUB 300
360 F=0:X=DX:Y=DY:GOSUB 300
370 F=3:X=X2:Y=Y2:GOSUB 300
380 END 
500 IF RR=0THEN RETURN 
505 X=X-OX:Y=Y-OY:FOR Q=1TO RR
510 QX=X*-.5-Y*R:QY=X*R+Y*-.5
520 X=QX:Y=QY
530 NEXT Q
540 X=X+OX:Y=Y+OY
550 RETURN 
