EntityQ2500408· pop 12· linked from 6 articlesThébault's theoremSign in to saveone of three theorems in geometry proved by French mathematician Victor ThébaultConnectionsFranceCountryNetherlandsConceptgeometryEntitytriangleEntitysquareEntitymathematicianEntityquadrilateralEntitymathematical proofEntitydigital object identifierEntityparallelogramEntityequilateral triangleEntityJSTOROrganizationtangentEntityincircle and excircles of a triangleEntityNapoleon's theoremEntityMathematical ReviewsEntityCasey’s theoremEntityvan Aubel's theoremEntityAmerican Mathematical MonthlyEntityForum GeometricorumEntityCategoriesTheorems about quadrilateralsTheorems about triangles and circles