Hinge Theorem: Triangle, Congruent, Angle, Shape

Van Aubel's Theorem: Quadrilateral, Square, Right Angle, Thébault's Theorem, Napoleon's Polygon, Triangle

Tunnell's Theorem: Congruent Number Problem, Rational

Barrow's Inequality: Geometry, Triangle, Angle Bisector, Euler's Theorem in Geometry

Exterior Angle Theorem: Theorem, Elementary Geometry,