By ∠(l,n) we always mean the directed angle of the lines l and n, taken modulo 180∘.

Let CC2 meet Ω again at K (as usual, if CC2 is tangent to Ω, we set K=C2). We show that the line BB2 contains K; similarly, AA2 will also pass through K. For this purpose, it suffices to prove that
∠(C2C,C2A1)=∠(B2B,B2A1).(1)
By the problem condition, CB and CA are the perpendicular bisectors of TA1 and TB1, respectively. Hence, C is the circumcenter of the triangle A1TB1. Therefore,
∠(CA1,CB1)=∠(CB,CT)=∠(B1A1,B1T)=∠(B1A1,B1B2).
In circle Ω we have ∠(B1A1,B1B2)=∠(C2A1,C2B2). Thus,
∠(CA1,CB)=∠(B1A1,B1B2)=∠(C2A1,C2B2).(2)
Similarly, we get
∠(BA1,BC)=∠(C1A1,C1C2)=∠(B2A1,B2C2).(3)
The two obtained relations yield that the triangles A1BC and A1B2C2 are similar and equioriented, hence
A1BA1B2=A1CA1C2and∠(A1B,A1C)=∠(A1B2,A1C2).
The second equality may be rewritten as ∠(A1B,A1B2)=∠(A1C,A1C2), so the triangles A1BB2 and A1CC2 are also similar and equioriented. This establishes (1). □