**Tags: Euclid**

Tags: Euclid, Elements, Geometry, Parallelogram, Triangle, Angle

Tags: Euclid, Elements, Geometry, Equilateral, Triangle

Tags: Euclid, Elements, Geometry, Square, Quadrilateral

Tags: Euclid, Elements, Geometry, Parallelogram, Triangle

Tags: Euclid, Elements, Geometry, Pythagorean, Theorem