Theorems concerning quadrilateral properties

Triangle congruence is not only useful when working with triangles, it's also useful with any other kind of polygon! Prove a few theorems about the properties of parallelograms using triangle congruence.

Proof: Opposite sides of a parallelogram

Proof: Diagonals of a parallelogram

Proof: Opposite angles of a parallelogram

Proof: The diagonals of a kite are perpendicular

Proof: Rhombus diagonals are perpendicular bisectors

Proof: Rhombus area

Prove parallelogram properties