Every finitely presented group has presentation satisfying $C'(1/5)$. Note that $1/5 < 5/11$. See the book by Lyndon and SchuppOlshanskii's book "Geometry of defining relations of groups".
Every finitely presented group has presentation satisfying $C'(1/5)$. Note that $1/5 < 5/11$. See the book by Lyndon and Schupp.