# Incenter/Escenter Theorem
Let(A=[-u1,0], B=[u1,0], C=[u2,u3], A1=[0,x1], B1=[0,x2], C1=[0,x3]):
Incenter := Theorem(
   [arbitrary(A,B,C), equiangle(C,A,A1,A1,A,B), equiangle(A,B,B1,B1,B,C),
    equiangle(B,C,C1,C1,C,A)], concurrent(A,A1,B,B1,C,C1), [x1,x2,x3]);
