ADGEOM 893

Dear All Friends,

Let four circles (A); (B); (C) and (P ) with center A; B; C and P (respectively), such that P is radical center of three circles (A); (B); (C). Denote (a); (b); (c) respectively are the radical axis of (P ) and (A); (B); (C). Denote (b) meets (c) at A1, (c) meets (a) at B1, (a)  meets (b) at C1. Then AA1; BB1; CC1 are concurrent(at D).  Let radius of the circle (A),(B),(C), (P) respectively are Ra, Rb, Rc, Rp.

Would you like answer me the locus (coordinates) of the perspector?

Best regards

Sincerely

Dao Thanh Oai