(* Napoleon Triangle *)

Lemma l_6_191 : forall A B C  E F G O1 O2 O3 r,
1+2<>0 ->
r*r = (2+1) ->
is_midpoint E A C ->
on_perp_d O2 E A (r / (2+1)) ->
is_midpoint F B C ->
on_perp_d O1 F C (r / (2+1)) ->
is_midpoint G A B ->
on_perp_d O3 G B (r/ (2+1)) ->
eq_distance O1 O2 O2 O3.