Monge & d'Alembert Three Circles Theorem II

Dynamic Geometry
Given three disjoint circles A, B and C of unequal radii situated entirely in each other's exterior, the common internal tangents of circles A and C meet in Y, the common internal tangents of circles A and B meet in Z and the common external tangents of circles B and C meet in X. Then the points X, Y and Z are collinear.


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