Section Circumcenter.
Context `{TE:Tarski_euclidean}.
Definition is_circumcenter G A B C := Cong A G B G /\ Cong B G C G /\ Coplanar G A B C.

Lemma circumcenter_cong : forall G A B C,
is_circumcenter G A B C ->
Cong A G B G /\ Cong B G C G /\ Cong C G A G.