PRINT CHR$(12)
PRINT
PRINT "ENTER THE THREE VERTEXES OF THE TRIANGLE:";
PRINT
PRINT "POINT A (X,Y) ";
INPUT X1,Y1
PRINT "POINT B (X,Y) ";
INPUT X2,Y2
PRINT "POINT C (X,Y) ";
INPUT X3,Y3
PRINT
PRINT
PRINT
PRINT "POINT A : (";X1;",";Y1;")"
PRINT "POINT B : (";X2;",";Y2;")"
PRINT "POINT C : (";X3;",";Y3;")"
PRINT
GOSUB CHECK
IF E=1 THEN PRINT"YOU CAN'T DO THAT!":GOSUB WKEY:RUN
PRINT "PRESS ANY KEY TO START"
IOP=0
GOSUB WKEY
GOSUB PICIT
PRINT "PRESS A KEY"
GOSUB WKEY
GOSUB SLOPE
GOSUB EQAT
GOSUB WKEY
GOSUB MEDIAN
GOSUB CIRCUM
GOSUB ORTHO
GOSUB EULER
PRINT "PRESS A KEY TO START OVER"
GOSUB WKEY
RUN
END

INFORM:
PRINT
PRINT
PRINT "INTERCEPT - "
PRINT
PRINT "WRITTEN BY: Michael Kohn"
PRINT
PRINT "KNOWEN BUGS: NONE"
PRINT 
PRINT "DATE FINISHED: DECEMBER 1, 1989"
PRINT
PRINT
PRINT "PRESS A KEY TO START OVER"
GOSUB WKEY
RETURN

EULER:
GOSUB PICIT
P=L1:O=L2
I=L3:U=L4:GOSUB PLOTIT
CIRCLE (P,O),2,2
CIRCLE (I,U),2,2
I=L3:U=L4
P=L5:O=L6:GOSUB PLOTIT
CIRCLE (P,O),2,2
PRINT "EULER LINE"
PRINT
PRINT "PRESS A KEY TO CONTINUE"
GOSUB WKEY
PRINT CHR$(12);
PRINT
PRINT
GNR1=YR(1)*YT(2)-YR(2)*YT(1)
GMR1=XR(1)*XT(2)-XR(2)*XT(1)
GNR2=YR(1)*YR(2)
GMR2=XR(1)*XR(2)
Q=GNR1:W=GNR2:GOSUB REDUCE
GNR1=Q:GNR2=W
Q=GMR1:W=GMR2:GOSUB REDUCE
GMR1=Q:GMR2=W
SY=GNR1*GMR2
SX=GNR2*GMR1
Q=SY:W=SX:GOSUB REDUCE:SY=Q:SX=W
SLOPE$=STR$(SY)+"/"+STR$(SX)
IF SX=1 THEN SLOPE$=STR$(SY)
PRINT
PRINT "SLOPE OF EULER LINE : ";SLOPE$
Q1=YT(1):Q2=YR(1)
W1=XT(1):W2=XR(1):W4=SY:W3=SX
PRINT "EQUATION OF EULER LINE : Y=";SY;"/";SX;"X";
GOSUB AL
PRINT K$
PRINT
PRINT
RETURN

ORTHO:
GOSUB PICIT
P=X3:O=Y3
I=P:U=O
IF SY1>=SX1 THEN BINX=INY/2
IF SY1<=SX1 THEN BINX=INX/2
FOR JK=1 TO BINX
I=I+SY1:U=U-SX1
P=P-SY1:O=O+SX1
NEXT JK
GOSUB PLOTIT
P=X1:O=Y1
I=P:U=O
IF SY2>=SX2 THEN BINX=INY/2
IF SY2<=SX2 THEN BINX=INX/2
FOR JK=1 TO BINX
I=I+SY2:U=U-SX2
P=P-SY2:O=O+SX2
NEXT JK
GOSUB PLOTIT
P=X2:O=Y2
I=P:U=O
IF SY3>=SX3 THEN BINX=INY/2
IF SY3<=SX3 THEN BINX=INX/2
FOR JK=1 TO BINX
I=I+SY3:U=U-SX3
P=P-SY3:O=O+SX3
NEXT JK
GOSUB PLOTIT
PRINT "ORTHOCENTER"
PRINT
PRINT "PRESS ANY KEY"
GOSUB WKEY
PRINT CHR$(12);
PRINT "POINT A : (";X1;",";Y1;")"
PRINT "POINT B : (";X2;",";Y2;")"
PRINT "POINT C : (";X3;",";Y3;")"
PRINT
PRINT "THE SLOPE OF ALTITUDE THROUGH A IS ";SPY2;"/";SPX2
PRINT "THE SLOPE OF ALTITUDE THROUGH B IS ";SPY3;"/";SPX3
PRINT "THE SLOPE OF ALTITUDE THROUGH C IS ";SPY1;"/";SPX1
PRINT
Q1=Y1:Q2=1
W1=X1:W2=1:W4=SPY2:W3=SPX2
PRINT "EQUATION OF ALTITUDE THROUGH A IS : Y=";SPY2;"/";SPX2;"X";
GOSUB AL
PRINT K$:KEA1=K1:KEA2=K2
Q1=Y2:Q2=1
W1=X2:W2=1:W4=SPY3:W3=SPX3
PRINT "EQUATION OF ALTITUDE THROUGH B IS : Y=";SPY3;"/";SPX3;"X";
GOSUB AL
PRINT K$:KEB1=K1:KEB2=K2
Q1=Y3:Q2=1
W1=X3:W2=1:W4=SPY1:W3=SPX1
PRINT "EQUATION OF ALTITUDE THROUGH C IS : Y=";SPY1;"/";SPX1;"X";
GOSUB AL
PRINT K$:KEC1=K1:KEC2=K2
PRINT
PRINT
PRINT "ORTHOCENTER : ";
ZZ=0:ZX=0
IF SPX2<>0 THEN B1=1:B2=1:A1=SPY2:A2=SPX2:C1=KEA1:C2=KEA2:ZZ=1
IF SPX3<>0 THEN E1=1:E2=1:D1=SPY3:D2=SPX3:F1=KEB1:F2=KEB2:ZX=1
IF SPX1<>0 AND ZZ=0 THEN B1=1:B2=1:A1=SPY1:A2=SPX1:C1=KEC1:C2=KEC2:ZZ=1
IF SPX1<>0 AND ZX=0 THEN E1=1:E2=1:D1=SPY1:D2=SPX1:F1=KEC1:F2=KEC2:ZX=1
IF ZZ<>1 OR ZX<>1 THEN PRINT "ERROR - NOT ENOUGH INFO"
A1=-A1:D1=-D1
GOSUB DETER
LOCATE 14,15
PRINT "(";XX$;",";YY$;")"
IF DEC=1 THEN PRINT "OR       : ";DEC$
L5=McZIP1:L6=McZIP2
PRINT
PRINT
PRINT "PRESS ANY KEY TO CONTINUE"
GOSUB WKEY
RETURN

CIRCUM:
GOSUB PICIT
P=(X1+X2)/2:O=(Y1+Y2)/2
I=P:U=O
IF SY1>=SX1 THEN BINX=INY/2
IF SY1<=SX1 THEN BINX=INX/2
FOR JK=1 TO BINX
I=I+SY1:U=U-SX1
P=P-SY1:O=O+SX1
NEXT JK
GOSUB PLOTIT
P=(X2+X3)/2:O=(Y2+Y3)/2
I=P:U=O
IF SY2>=SX2 THEN BINX=INY/2
IF SY2<=SX2 THEN BINX=INX/2
FOR JK=1 TO BINX
I=I+SY2:U=U-SX2
P=P-SY2:O=O+SX2
NEXT JK
GOSUB PLOTIT
P=(X1+X3)/2:O=(Y1+Y3)/2
I=P:U=O
IF SY3>=SX3 THEN BINX=INY/2
IF SY3<=SX3 THEN BINX=INX/2
FOR JK=1 TO BINX
I=I+SY3:U=U-SX3
P=P-SY3:O=O+SX3
NEXT JK
GOSUB PLOTIT
PRINT "CIRCUMCENTER"
PRINT
PRINT "PRESS A KEY"
GOSUB WKEY
PRINT CHR$(12);
PRINT "POINT A : (";X1;",";Y1;")"
PRINT "POINT B : (";X2;",";Y2;")"
PRINT "POINT C : (";X3;",";Y3;")"
PRINT
PRINT "MIDPOINT OF LINE AB : (";M1;",";N1;")"
PRINT "MIDPOINT OF LINE BC : (";M2;",";N2;")"
PRINT "MIDPOINT OF LINE CA : (";M3;",";N3;")"
PRINT
SPY1=-SX1:SPX1=SY1
SPY2=-SX2:SPX2=SY2
SPY3=-SX3:SPX3=SY3
IF SPX1<0 THEN SPY1=-SPY1:SPX1=-SPX1
IF SPX2<0 THEN SPY2=-SPY2:SPX2=-SPX2
IF SPX3<0 THEN SPY3=-SPY3:SPX3=-SPX3
PRINT "THE SLOPE OF THE LINE PERPENDICULAR TO AB IS ";SPY1;"/";SPX1
PRINT "THE SLOPE OF THE LINE PERPENDICULAR TO BC IS ";SPY2;"/";SPX2
PRINT "THE SLOPE OF THE LINE PERPENDICULAR TO CA IS ";SPY3;"/";SPX3
PRINT
Q1=Y2+Y1:Q2=2
W1=X2+X1:W2=2:W4=SPY1:W3=SPX1
PRINT "EQUATION OF PERPENDICULAR BISECTOR OF AB IS : Y=";SPY1;"/";SPX1;"X";
GOSUB AL
PRINT K$:KIA1=K1:KIA2=K2
Q1=Y2+Y3:Q2=2
W1=X2+X3:W2=2:W4=SPY2:W3=SPX2
PRINT "EQUATION OF PERPENDICULAR BISECTOR OF BC IS : Y=";SPY2;"/";SPX2;"X";
GOSUB AL
PRINT K$:KIB1=K1:KIB2=K2
Q1=Y3+Y1:Q2=2
W1=X3+X1:W2=2:W4=SPY3:W3=SPX3
PRINT "EQUATION OF PERPENDICULAR BISECTOR OF CA IS : Y=";SPY3;"/";SPX3;"X";
GOSUB AL
PRINT K$:KIC1=K1:KIC2=K2
PRINT
PRINT
PRINT "CIRCUMCENTER : ";
ZZ=0:ZX=0
IF SPX1<>0 THEN B1=1:B2=1:A1=SPY1:A2=SPX1:C1=KIA1:C2=KIA2:ZZ=1
IF SPX2<>0 THEN E1=1:E2=1:D1=SPY2:D2=SPX2:F1=KIB1:F2=KIB2:ZX=1
IF SPX3<>0 AND ZZ=0 THEN B1=1:B2=1:A1=SPY3:A2=SPX3:C1=KIC1:C2=KIC2:ZZ=1
IF SPX3<>0 AND ZX=0 THEN E1=1:E2=1:D1=SPY3:D2=SPX3:F1=KIC1:F2=KIC2:ZX=1
IF ZZ<>1 OR ZX<>1 THEN PRINT "ERROR - NOT ENOUGH INFO"
A1=-A1:D1=-D1
GOSUB DETER
LOCATE 18,16
PRINT "(";XX$;",";YY$;")"
IF DEC=1 THEN PRINT "OR       : ";DEC$
L3=McZIP1:L4=McZIP2
PRINT
PRINT
PRINT "PRESS ANY KEY TO CONTINUE"
GOSUB WKEY
RETURN

PLOTIT:
P=P*INX:P=P+300
O=-O*INY:O=O+100
I=I*INX:I=I+300
U=-U*INY:U=U+100
LINE (P,O)-(I,U),3
RETURN

MEDIAN:
GOSUB PICIT
P=(X1+X2)/2:P=P*INX:P=P+300       
O=(Y1+Y2)/2:O=-O*INY:O=O+100
I=X3*INX:I=I+300
U=-Y3*INY:U=U+100
LINE (P,O)-(I,U),3
P=(X2+X3)/2:P=P*INX:P=P+300
O=(Y2+Y3)/2:O=-O*INY:O=O+100
I=X1*INX:I=I+300
U=-Y1*INY:U=U+100
LINE (P,O)-(I,U),3
P=(X1+X3)/2:P=P*INX:P=P+300
O=(Y1+Y3)/2:O=-O*INY:O=O+100
I=X2*INX:I=I+300
U=-Y2*INY:U=U+100
LINE (P,O)-(I,U),3
PRINT "CENTROID"
PRINT
PRINT "PRESS ANY KEY"
GOSUB WKEY
PRINT CHR$(12);
PRINT "POINT A : (";X1;",";Y1;")"
PRINT "POINT B : (";X2;",";Y2;")"
PRINT "POINT C : (";X3;",";Y3;")"
PRINT
M1=(X1+X2)/2:N1=(Y1+Y2)/2
M2=(X2+X3)/2:N2=(Y2+Y3)/2
M3=(X3+X1)/2:N3=(Y3+Y1)/2
PRINT "MIDPOINT OF LINE AB : (";M1;",";N1;")"
PRINT "MIDPOINT OF LINE BC : (";M2;",";N2;")"
PRINT "MIDPOINT OF LINE CA : (";M3;",";N3;")"
PRINT
SMY1=N1-Y3:SMX1=M1-X3
SMY2=N2-Y1:SMX2=M2-X1
SMY3=N3-Y2:SMX3=M3-X2
IF SMY1<>INT(SMY1) OR SMX1<>INT(SMX1) THEN SMX1=SMX1*2:SMY1=SMY1*2
IF SMY2<>INT(SMY2) OR SMX1<>INT(SMX2) THEN SMX2=SMX2*2:SMY2=SMY2*2
IF SMY3<>INT(SMY3) OR SMX1<>INT(SMX3) THEN SMX3=SMX3*2:SMY3=SMY3*2
Q=SMY1:W=SMX1:GOSUB REDUCE:SMY1=Q:SMX1=W
Q=SMY2:W=SMX2:GOSUB REDUCE:SMY2=Q:SMX2=W
Q=SMY3:W=SMX3:GOSUB REDUCE:SMY3=Q:SMX3=W
IF SMX1<0 THEN SMX1=-SMX1:SMY1=-SMY1
IF SMX2<0 THEN SMX2=-SMX2:SMY2=-SMY2
IF SMX3<0 THEN SMX3=-SMX3:SMY3=-SMY3
PRINT "SLOPE OF MEDIAN A : ";SMY2;"/";SMX2
PRINT "SLOPE OF MEDIAN B : ";SMY3;"/";SMX3
PRINT "SLOPE OF MEDIAN C : ";SMY1;"/";SMX1
PRINT
Q1=Y2+Y3:Q2=2
W1=X2+X3:W2=2:W4=SMY2:W3=SMX2
PRINT "EQUATION OF MEDIAN A : Y=";SMY2;"/";SMX2;"X";
GOSUB AL
PRINT K$:KA1=K1:KA2=K2
Q1=Y1+Y3:Q2=2
W1=X1+X3:W2=2:W4=SMY3:W3=SMX3
PRINT "EQUATION OF MEDIAN B : Y=";SMY3;"/";SMX3;"X";
GOSUB AL
PRINT K$:KB1=K1:KB2=K2
Q1=Y1+Y2:Q2=2
W1=X1+X2:W2=2:W4=SMY1:W3=SMX1
PRINT "EQUATION OF MEDIAN C : Y=";SMY1;"/";SMX1;"X";
GOSUB AL
PRINT K$:KC1=K1:KC2=K2
PRINT
PRINT
PRINT "CENTROID : ";
ZZ=0:ZX=0
IF SMX1<>0 THEN B1=1:B2=1:A1=SMY1:A2=SMX1:C1=KC1:C2=KC2:ZZ=1
IF SMX2<>0 THEN E1=1:E2=1:D1=SMY2:D2=SMX2:F1=KA1:F2=KA2:ZX=1
IF SMX3<>0 AND ZZ=0 THEN B1=1:B2=1:A1=SMY3:A2=SMX3:C1=KB1:C2=KB2:ZZ=1
IF SMX3<>0 AND ZX=0 THEN E1=1:E2=1:D1=SMY3:D2=SMX3:F1=KB1:F2=KB2:ZX=1
IF ZZ<>1 OR ZX<>1 THEN PRINT "ERROR - NOT ENOUGH INFO"
A1=-A1:D1=-D1
GOSUB DETER
LOCATE 18,12
PRINT "(";XX$;",";YY$;")"
IF DEC=1 THEN PRINT "OR       : ";DEC$
L1=McZIP1:L2=McZIP2
PRINT
PRINT
PRINT "PRESS ANY KEY TO CONTINUE"
GOSUB WKEY
RETURN

DETER:
IOP=IOP+1:DEC=0
XX1=A2*B2*C2
XX2=D2*E2*F2
A1=A1*XX1:B1=B1*XX1:C1=C1*XX1
D1=D1*XX2:E1=E1*XX2:F1=F1*XX2
LOCATE 18,40:PRINT"REDUCING.";
Q=A1:W=A2:GOSUB REDUCE:A1=Q:A2=W:PRINT".";   
Q=B1:W=B2:GOSUB REDUCE:B1=Q:B2=W:PRINT".";
Q=C1:W=C2:GOSUB REDUCE:C1=Q:C2=W:PRINT".";
Q=D1:W=D2:GOSUB REDUCE:D1=Q:D2=W:PRINT".";
Q=E1:W=E2:GOSUB REDUCE:E1=Q:E2=W:PRINT".";
Q=F1:W=F2:GOSUB REDUCE:F1=Q:F2=W:PRINT".";
IF A2<>1 OR B2<>1 OR C2<>1 THEN PRINT"ERROR":END
IF D2<>1 OR E2<>1 OR F2<>1 THEN PRINT"ERROR":END
XX1=(C1*E1)-(F1*B1)
XX2=(A1*E1)-(D1*B1)
YY1=(A1*F1)-(D1*C1)
YY2=(A1*E1)-(D1*B1)
Q=XX1:W=XX2:GOSUB REDUCE:XX1=Q:XX2=W:PRINT".";
Q=YY1:W=YY2:GOSUB REDUCE:YY1=Q:YY2=W:PRINT".";
XX$=STR$(XX1)+"/"+STR$(XX2)
YY$=STR$(YY1)+"/"+STR$(YY2)
IF XX2=1 THEN XX$=STR$(XX1)
IF YY2=1 THEN YY$=STR$(YY1)
IF XX2<>1 OR YY2<>1 THEN DEC=1:DEC$="("+STR$(XX1/XX2)+","+STR$(YY1/YY2)+")"
McZIP1=XX1/XX2:McZIP2=YY1/YY2
XT(IOP)=XX1:YT(IOP)=YY1
XR(IOP)=XX2:YR(IOP)=YY2
LOCATE 18,40:PRINT"                 "
RETURN

AL:
IF W3=0 THEN W2=0:GOTO McSKIPPY
Q=W4*W1:W=W3*W2:GOSUB REDUCE:W1=Q:W2=W:W3=W
IF Q2<0 THEN Q2=-Q2:Q1=-Q1
IF W2<0 THEN W2=-W2:W1=-W1:W3=-W3
W1=W1*Q2:W2=W2*Q2
Q2=Q2*W3:Q1=Q1*W3
IF Q2<>W2 THEN PRINT "ERROR":END
Q1=Q1-W1
Q=Q1:W=Q2:GOSUB REDUCE:Q1=Q:Q2=W
IF Q1<0 THEN K$=STR$(Q1)+"/"+STR$(Q2)
IF Q1>0 THEN K$="+"+STR$(Q1)+"/"+STR$(Q2)
IF Q1=0 THEN K$="+0"
IF Q2=1 AND Q1<0 THEN K$=STR$(Q1)
IF Q2=1 AND Q1>0 THEN K$="+"+STR$(Q1)
K1=Q1:K2=Q2
RETURN

EQAT:
SL1$=STR$(SY1)+"/"+MID$(STR$(SX1),2,5)
SL2$=STR$(SY2)+"/"+MID$(STR$(SX2),2,5)
SL3$=STR$(SY3)+"/"+MID$(STR$(SX3),2,5)
IF SY1=SX1 THEN SL1$="1"
IF SY2=SX2 THEN SL2$="1"
IF SY3=SX3 THEN SL3$="1"
IF SY1=-SX1 THEN SL1$="-1"
IF SY2=-SX2 THEN SL2$="-1"
IF SY3=-SX3 THEN SL3$="-1"
PRINT "EQUATION OF LINE AB : Y=";SL1$;"X";
Q1=Y1:Q2=1
W1=X1:W2=SX1:W1=W1*SY1
GOSUB ALGEBRA
PRINT K$
PRINT "EQUATION OF LINE BC : Y=";SL2$;"X";
Q1=Y2:Q2=1
W1=X2:W2=SX2:W1=W1*SY2
GOSUB ALGEBRA
PRINT K$
PRINT "EQUATION OF LINE CA : Y=";SL3$;"X";
Q1=Y3:Q2=1
W1=X3:W2=SX3:W1=W1*SY3
GOSUB ALGEBRA
PRINT K$
PRINT
PRINT
PRINT "PRESS A KEY TO CONTINUE"
RETURN

ALGEBRA:
IF W2=0 THEN GOTO McSKIPPY
Q=W1:W=W2:GOSUB REDUCE
W1=Q:W2=W
Q2=W2:Q1=Q1*Q2
Q1=Q1-W1
Q=Q1:W=Q2:GOSUB REDUCE
Q1=Q:Q2=W
IF Q2<0 THEN Q2=Q2*-1:Q1=Q1*-1
IF Q1<0 THEN K$=STR$(Q1)+"/"+STR$(Q2)
IF Q1>0 THEN K$="+"+STR$(Q1)+"/"+STR$(Q2)
IF Q2=1 AND Q1>0 THEN K$="+"+STR$(Q1)
IF Q2=1 AND Q1<0 THEN K$=STR$(Q1)
IF Q1=0 THEN K$="+0"
McSKIPPY:
IF W2=0 THEN K$=" - VERTICLE LINE"
RETURN

SLOPE:
SY1=(Y1-Y2):SX1=(X1-X2)
SY2=(Y2-Y3):SX2=(X2-X3)
SY3=(Y1-Y3):SX3=(X1-X3)
Q=SY1:W=SX1:GOSUB REDUCE:SY1=Q:SX1=W
Q=SY2:W=SX2:GOSUB REDUCE:SY2=Q:SX2=W
Q=SY3:W=SX3:GOSUB REDUCE:SY3=Q:SX3=W
PRINT CHR$(12)
PRINT
PRINT "POINT A : (";X1;",";Y1;")"
PRINT "POINT B : (";X2;",";Y2;")"
PRINT "POINT C : (";X3;",";Y3;")"
PRINT
PRINT
IF SX1<0 THEN SY1=-SY1:SX1=-SX1
IF SX2<0 THEN SY2=-SY2:SX2=-SX2
IF SX3<0 THEN SY3=-SY3:SX3=-SX3
PRINT "THE SLOPE OF LINE AB IS ";SY1;"/";SX1
PRINT "THE SLOPE OF LINE BC IS ";SY2;"/";SX2
PRINT "THE SLOPE OF LINE CA IS ";SY3;"/";SX3
PRINT
PRINT
RETURN

REDUCE:
IF Q/5=INT(Q/5) AND W/5=INT(W/5) THEN Q=Q/5:W=W/5:GOTO REDUCE
IF Q/2=INT(Q/2) AND W/2=INT(W/2) THEN Q=Q/2:W=W/2:GOTO REDUCE
IF Q/3=INT(Q/3) AND W/3=INT(W/3) THEN Q=Q/3:W=W/3:GOTO REDUCE
IF Q>W THEN QW=Q
IF Q<W THEN QW=W
IF Q=W THEN QW=1:Q=1:W=1
FOR T=QW TO 2 STEP -1
IF INT(Q/T)=Q/T AND INT(W/T)=W/T THEN Q=Q/T:W=W/T:T=T+1 
NEXT T
IF W<0 THEN W=-W:Q=-Q
RETURN

CHECK:
IF X1=X2 AND Y1=Y2 THEN E=1
IF X1=X3 AND Y1=Y3 THEN E=1
IF X3=X2 AND Y3=Y2 THEN E=1
RETURN

WKEY:
G$=INKEY$
IF G$="" THEN WKEY
RETURN

PICIT:
GOSUB SETIT
X=X1*INX:X=X+300
Y=-Y1*INY:Y=Y+100
M=X2*INX:M=M+300
N=-Y2*INY:N=N+100
LINE (X,Y)-(M,N),1
CIRCLE (X,Y),2,1
CIRCLE (M,N),2,1
M=X3*INX:M=M+300
N=-Y3*INY:N=N+100
LINE (X,Y)-(M,N),1
CIRCLE (M,N),2,1
X=X2*INX:X=X+300
Y=-Y2*INY:Y=Y+100
LINE (X,Y)-(M,N),1
REM 13,38 IS CENTER
RETURN

SETIT:
PRINT CHR$(12)
INX=10
INY=10
A=X1:B=X1:C=Y1:D=Y1
IF X2>A THEN A=X2
IF X3>A THEN A=X3
IF X2<B THEN B=X2
IF X3<B THEN B=X3
IF Y2>C THEN C=Y2
IF Y3>C THEN C=Y3
IF Y2<D THEN D=Y2
IF Y3<D THEN D=Y3
IF A<30 OR B>-30 THEN INX=10
IF A>29 OR B<-29 THEN INX=5
IF C<8 OR D>-8 THEN INY=10
IF C>7 OR D<-7 THEN INY=5
IF A<15 OR B>-15 THEN INX=20
COLOR 3,0
ER=(((-Y1*INY)+100)/8)+1
TY=((( X1*INX)+300)/8)+1
LOCATE ER,TY:PRINT"A"
ER=(((-Y2*INY)+100)/8)+1
TY=((( X2*INX)+300)/8)+1
LOCATE ER,TY:PRINT"B" 
ER=(((-Y3*INY)+100)/8)+1
TY=((( X3*INX)+300)/8)+1
LOCATE ER,TY:PRINT"C" 
COLOR 1,0:LOCATE 1,1
LINE (1,100)-(600,100),2
LINE (300,1)-(300,200),2
FOR T=100 TO 200 STEP INY
LINE (298,T)-(302,T),2
NEXT T
FOR T=100 TO 1 STEP -INY
LINE (298,T)-(302,T),2
NEXT T
FOR T=300 TO 600 STEP INX
LINE (T,98)-(T,102),2
NEXT T
FOR T=300 TO 1 STEP -INX
LINE (T,98)-(T,102),2
NEXT
RETURN