Peter Nachtwey schrieb:   
   >   
   > Thanks Nasser,  I got a solution but it was big.  Trying   
   > FullSimplify[%] now.   
   >   
      
   Here's that solution by Derive 6.10. It's actually four closely related   
   solutions, and I wouldn't call them big:   
      
   [x0=(r*(SQRT(m0^2+1)+SQRT(m1^2+1))*SQRT(2*m0*m1*SQRT(m0^2+1)*SQR~   
   T(m1^2+1)+m0^2*(2*m1^2+1)+m1^2)*SIGN(m0-m1)+(b0-b1)*(m0+m1)*SQRT~   
   (m0^2+1))/((m0+m1)*SQRT(m0^2+1)*(m1-m0)) AND x1=(r*(SQRT(m0^2+1)~   
   +SQRT(m1^2+1))*SQRT(2*m0*m1*SQRT(m0^2+1)*SQRT(m1^2+1)+m0^2*(2*m1~   
   ^2+1)+m1^2)*SIGN(m0-m1)+(b0-b1)*(m0+m1)*SQRT(m1^2+1))/((m0+m1)*(~   
   m1-m0)*SQRT(m1^2+1)) AND xc=(r*SQRT(2*m0*m1*SQRT(m0^2+1)*SQRT(m1~   
   ^2+1)+m0^2*(2*m1^2+1)+m1^2)*((m0-m1)*SQRT(m0^2+1)*SQRT(m1^2+1)-m~   
   0^2*m1+m0*(m1^2+1)-m1)*SIGN(m0-m1)+(b0-b1)*(m0^2-m1^2))/((m0^2-m~   
   1^2)*(m1-m0)) AND y0=(m0*r*(SQRT(m0^2+1)+SQRT(m1^2+1))*SQRT(2*m0~   
   *m1*SQRT(m0^2+1)*SQRT(m1^2+1)+m0^2*(2*m1^2+1)+m1^2)*SIGN(m0-m1)+~   
   (m0+m1)*SQRT(m0^2+1)*(b0*m1-b1*m0))/(SQRT(m0^2+1)*(m1^2-m0^2)) A~   
   ND y1=(m1*r*(SQRT(m0^2+1)+SQRT(m1^2+1))*SQRT(2*m0*m1*SQRT(m0^2+1~   
   )*SQRT(m1^2+1)+m0^2*(2*m1^2+1)+m1^2)*SIGN(m0-m1)+(m0+m1)*SQRT(m1~   
   ^2+1)*(b0*m1-b1*m0))/((m1^2-m0^2)*SQRT(m1^2+1)) AND yc=(b0*m1-b1~   
   *m0)/(m1-m0)-r*SQRT(2*m0*m1*SQRT(m0^2+1)*SQRT(m1^2+1)+m0^2*(2*m1~   
   ^2+1)+m1^2)/ABS(m0-m1),x0=(r*(SQRT(m0^2+1)+SQRT(m1^2+1))*SQRT(2*~   
   m0*m1*SQRT(m0^2+1)*SQRT(m1^2+1)+m0^2*(2*m1^2+1)+m1^2)*SIGN(m0-m1~   
   )-(b0-b1)*(m0+m1)*SQRT(m0^2+1))/((m0+m1)*(m0-m1)*SQRT(m0^2+1)) A~   
   ND x1=(r*(SQRT(m0^2+1)+SQRT(m1^2+1))*SQRT(2*m0*m1*SQRT(m0^2+1)*S~   
   QRT(m1^2+1)+m0^2*(2*m1^2+1)+m1^2)*SIGN(m0-m1)-(b0-b1)*(m0+m1)*SQ~   
   RT(m1^2+1))/((m0+m1)*(m0-m1)*SQRT(m1^2+1)) AND xc=(r*SQRT(2*m0*m~   
   1*SQRT(m0^2+1)*SQRT(m1^2+1)+m0^2*(2*m1^2+1)+m1^2)*((m0-m1)*SQRT(~   
   m0^2+1)*SQRT(m1^2+1)-m0^2*m1+m0*(m1^2+1)-m1)*SIGN(m0-m1)+(b0-b1)~   
   *(m1^2-m0^2))/((m0-m1)*(m0^2-m1^2)) AND y0=(m0*r*(SQRT(m0^2+1)+S~   
   QRT(m1^2+1))*SQRT(2*m0*m1*SQRT(m0^2+1)*SQRT(m1^2+1)+m0^2*(2*m1^2~   
   +1)+m1^2)*SIGN(m0-m1)-(m0+m1)*SQRT(m0^2+1)*(b0*m1-b1*m0))/(SQRT(~   
   m0^2+1)*(m0^2-m1^2)) AND y1=(m1*r*(SQRT(m0^2+1)+SQRT(m1^2+1))*SQ~   
   RT(2*m0*m1*SQRT(m0^2+1)*SQRT(m1^2+1)+m0^2*(2*m1^2+1)+m1^2)*SIGN(~   
   m0-m1)-(m0+m1)*SQRT(m1^2+1)*(b0*m1-b1*m0))/((m0^2-m1^2)*SQRT(m1^~   
   2+1)) AND yc=r*SQRT(2*m0*m1*SQRT(m0^2+1)*SQRT(m1^2+1)+m0^2*(2*m1~   
   ^2+1)+m1^2)/ABS(m0-m1)+(b0*m1-b1*m0)/(m1-m0),x0=(r*(SQRT(m0^2+1)~   
   -SQRT(m1^2+1))*SQRT(-2*m0*m1*SQRT(m0^2+1)*SQRT(m1^2+1)+m0^2*(2*m~   
   1^2+1)+m1^2)*SIGN(m0-m1)+(b0-b1)*(m0+m1)*SQRT(m0^2+1))/((m0+m1)*~   
   SQRT(m0^2+1)*(m1-m0)) AND x1=(r*(SQRT(m0^2+1)-SQRT(m1^2+1))*SQRT~   
   (-2*m0*m1*SQRT(m0^2+1)*SQRT(m1^2+1)+m0^2*(2*m1^2+1)+m1^2)*SIGN(m~   
   0-m1)-(b0-b1)*(m0+m1)*SQRT(m1^2+1))/((m0+m1)*(m0-m1)*SQRT(m1^2+1~   
   )) AND xc=(r*((m0-m1)*SQRT(m0^2+1)*SQRT(m1^2+1)+m0^2*m1-m0*(m1^2~   
   +1)+m1)*SQRT(-2*m0*m1*SQRT(m0^2+1)*SQRT(m1^2+1)+m0^2*(2*m1^2+1)+~   
   m1^2)*SIGN(m0-m1)+(b0-b1)*(m1^2-m0^2))/((m0-m1)*(m0^2-m1^2)) AND~   
    y0=(m0*r*(SQRT(m0^2+1)-SQRT(m1^2+1))*SQRT(-2*m0*m1*SQRT(m0^2+1)~   
   *SQRT(m1^2+1)+m0^2*(2*m1^2+1)+m1^2)*SIGN(m0-m1)+(m0+m1)*SQRT(m0^~   
   2+1)*(b0*m1-b1*m0))/(SQRT(m0^2+1)*(m1^2-m0^2)) AND y1=(m1*r*(SQR~   
   T(m0^2+1)-SQRT(m1^2+1))*SQRT(-2*m0*m1*SQRT(m0^2+1)*SQRT(m1^2+1)+~   
   m0^2*(2*m1^2+1)+m1^2)*SIGN(m0-m1)-(m0+m1)*SQRT(m1^2+1)*(b0*m1-b1~   
   *m0))/((m0^2-m1^2)*SQRT(m1^2+1)) AND yc=(b0*m1-b1*m0)/(m1-m0)-r*~   
   SQRT(-2*m0*m1*SQRT(m0^2+1)*SQRT(m1^2+1)+m0^2*(2*m1^2+1)+m1^2)/AB~   
   S(m0-m1),x0=(r*(SQRT(m0^2+1)-SQRT(m1^2+1))*SQRT(-2*m0*m1*SQRT(m0~   
   ^2+1)*SQRT(m1^2+1)+m0^2*(2*m1^2+1)+m1^2)*SIGN(m0-m1)-(b0-b1)*(m0~   
   +m1)*SQRT(m0^2+1))/((m0+m1)*(m0-m1)*SQRT(m0^2+1)) AND x1=(r*(SQR~   
   T(m0^2+1)-SQRT(m1^2+1))*SQRT(-2*m0*m1*SQRT(m0^2+1)*SQRT(m1^2+1)+~   
   m0^2*(2*m1^2+1)+m1^2)*SIGN(m0-m1)+(b0-b1)*(m0+m1)*SQRT(m1^2+1))/~   
   ((m0+m1)*(m1-m0)*SQRT(m1^2+1)) AND xc=(r*((m0-m1)*SQRT(m0^2+1)*S~   
   QRT(m1^2+1)+m0^2*m1-m0*(m1^2+1)+m1)*SQRT(-2*m0*m1*SQRT(m0^2+1)*S~   
   QRT(m1^2+1)+m0^2*(2*m1^2+1)+m1^2)*SIGN(m0-m1)+(b0-b1)*(m0^2-m1^2~   
   ))/((m0^2-m1^2)*(m1-m0)) AND y0=(m0*r*(SQRT(m0^2+1)-SQRT(m1^2+1)~   
   )*SQRT(-2*m0*m1*SQRT(m0^2+1)*SQRT(m1^2+1)+m0^2*(2*m1^2+1)+m1^2)*~   
   SIGN(m0-m1)-(m0+m1)*SQRT(m0^2+1)*(b0*m1-b1*m0))/(SQRT(m0^2+1)*(m~   
   0^2-m1^2)) AND y1=(m1*r*(SQRT(m0^2+1)-SQRT(m1^2+1))*SQRT(-2*m0*m~   
   1*SQRT(m0^2+1)*SQRT(m1^2+1)+m0^2*(2*m1^2+1)+m1^2)*SIGN(m0-m1)+(m~   
   0+m1)*SQRT(m1^2+1)*(b0*m1-b1*m0))/((m1^2-m0^2)*SQRT(m1^2+1)) AND~   
    yc=r*SQRT(-2*m0*m1*SQRT(m0^2+1)*SQRT(m1^2+1)+m0^2*(2*m1^2+1)+m1~   
   ^2)/ABS(m0-m1)+(b0*m1-b1*m0)/(m1-m0),x0-xc=0 AND x1*SQRT(m1^2+1)~   
   -xc*SQRT(m1^2+1)=m1*r AND y0=b0 AND y1=(b0*SQRT(m1^2+1)-r*(SQRT(~   
   m1^2+1)+1))/SQRT(m1^2+1) AND yc=b0-r AND m0=0,x0-xc=0 AND x1*SQR~   
   T(m1^2+1)-xc*SQRT(m1^2+1)=m1*r AND y0=b0 AND y1=(b0*SQRT(m1^2+1)~   
   +r*(SQRT(m1^2+1)-1))/SQRT(m1^2+1) AND yc=b0+r AND m0=0,x0-xc=0 A~   
   ND x1*SQRT(m1^2+1)-xc*SQRT(m1^2+1)=-m1*r AND y0=b0 AND y1=(b0*SQ~   
   RT(m1^2+1)+r*(SQRT(m1^2+1)+1))/SQRT(m1^2+1) AND yc=b0+r AND m0=0~   
   ,x0-xc=0 AND x1*SQRT(m1^2+1)-xc*SQRT(m1^2+1)=-m1*r AND y0=b0 AND~   
    y1=(b0*SQRT(m1^2+1)-r*(SQRT(m1^2+1)-1))/SQRT(m1^2+1) AND yc=b0-~   
   r AND m0=0,x0-xc+m0*(y0-b1-r)=0 AND x1-xc=0 AND m0*xc-y0*(m0^2+1~   
   )=-b0-m0^2*(b1+r) AND y1=b1 AND yc=b1+r AND m1=0,x0-xc+m0*(y0-b1~   
   +r)=0 AND x1-xc=0 AND m0*xc-y0*(m0^2+1)=-b0-m0^2*(b1-r) AND y1=b~   
   1 AND yc=b1-r AND m1=0]   
      
   The factor SIGN(m0-m1) can be set to 1 throughout, I think, as the sign   
   of the accompanying square root alternates betwen solutions.   
      
   Martin.   
      
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