fact: Definition inv O E E' A MA := (A <> O /\ Prod O E E' MA A E) \/ (A = O /\ MA = O).
imports: Description Ring Field Nsatz Rtauto GeoCoq.Tarski_dev.Ch16_coordinates GeoCoq.Tarski_dev.Ch15_pyth_rel GeoCoq.Tarski_dev.Annexes.midpoint_theorems