Monge's Theorem

Monge:=proc() local d1,d2,d3,C1,C2,C3,R1,R2,R3,a,b:

d1:=d3*sin(a)/sin(a+b):   d2:=d3*sin(b)/sin(a+b):   C1:=[0,0]:   C2:=[d3,0]:   C3:=[d2*cos(a),d2*sin(a)]:

Colinear (
CommonTangentsMeetingPt (C1,R1,a,d2,R3) , 
CommonTangentsMeetingPt (C3,R3,-b,d1,R2)  , 
CommonTangentsMeetingPt (C1,R1,0,d3,R2)
                 ):

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