Incenter Exists Theorem

IncenterExists:=proc() local m,n,A,B,C,T:

T:=Te(m,n):   A:=T[1]:   B:=T[2]:   C:=T[3]:

Concurrent( LePtSlope(A,m)   ,   LePtSlope(B,-n)   ,   LePtSlope(C, TS(m,1/n))):

end: