* code to solve for internal circle tangent to 3 circles
$$ NO,************************************* CIR1 =GENERIC/CIRCLE,DEPENDENT,CARTESIAN,OUT,$ NOM/XYZ,<0,0,0>,$ MEAS/XYZ,<0,0,0>,$ NOM/IJK,<0,0,1>,$ MEAS/IJK,<0,0,1>,$ RADIUS/1,1 $$ NO,************************************* CIR2 =GENERIC/CIRCLE,DEPENDENT,CARTESIAN,OUT,$ NOM/XYZ,<4,0,0>,$ MEAS/XYZ,<4,0,0>,$ NOM/IJK,<0,0,1>,$ MEAS/IJK,<0,0,1>,$ RADIUS/1,1 $$ NO,************************************* CIR3 =GENERIC/CIRCLE,DEPENDENT,CARTESIAN,OUT,$ NOM/XYZ,<2,4,0>,$ MEAS/XYZ,<2,4,0>,$ NOM/IJK,<0,0,1>,$ MEAS/IJK,<0,0,1>,$ RADIUS/2,2 $$ NO,************************************* ASSIGN/X1=CIR1.X ASSIGN/Y1=CIR1.Y ASSIGN/R1=CIR1.R $$ NO,************************************* ASSIGN/X2=CIR2.X ASSIGN/Y2=CIR2.Y ASSIGN/R2=CIR2.R $$ NO,************************************* ASSIGN/X3=CIR3.X ASSIGN/Y3=CIR3.Y ASSIGN/R3=CIR3.R $$ NO,************************************* $$ NO,***** S1 S2 S3 ALL -1 FOR INTERNAL TANGENT CIRCLE ***** $$ NO,************************************* ASSIGN/S1=-1 ASSIGN/S2=-1 ASSIGN/S3=-1 $$ NO,************************************* ASSIGN/V11=2*(X2-X1) ASSIGN/V12=2*(Y2-Y1) ASSIGN/V13=(X1^2)-(X2^2)+(Y1^2)-(Y2^2)-(R1^2)+(R2^2) ASSIGN/V14=2*(S2*R2)-2*(S1*R1) $$ NO,************************************* ASSIGN/V21=(2*X3)-(2*X2) ASSIGN/V22=(2*Y3)-(2*Y2) ASSIGN/V23=(X2^2)-(X3^2)+(Y2^2)-(Y3^2)-(R2^2)+(R3^2) ASSIGN/V24=2*(S3*R3)-2*(S2*R2) $$ NO,************************************* ASSIGN/W12=V12/V11 ASSIGN/W13=V13/V11 ASSIGN/W14=V14/V11 $$ NO,************************************* ASSIGN/W22=(V22/V21)-W12 ASSIGN/W23=(V23/V21)-W13 ASSIGN/W24=(V24/V21)-W14 $$ NO,************************************* ASSIGN/P=0-(W23/W22) ASSIGN/Q=W24/W22 ASSIGN/M=0-(W12*P)-W13 ASSIGN/N=W14-(W12*Q) $$ NO,************************************* ASSIGN/A=(N^2)+(Q^2)-1 ASSIGN/B=(2*M*N)-(2*N*X1)+2*(P*Q)-2*(Q*Y1)+2*(S1*R1) ASSIGN/C=(X1^2)+(M^2)-2*(M*X1)+(P^2)+(Y1^2)-2*(P*Y1)-(R1^2) $$ NO,************************************* ASSIGN/D=(B^2)-4*A*C $$ NO,************************************* ASSIGN/RADIUS=(0-(B)-(SQRT(D)))/(2*A) ASSIGN/XPOS=M+N*RADIUS ASSIGN/YPOS=P+Q*RADIUS $$ NO,*************************************
Use as you wish.