Definition:Complements of Parallelograms

Definition
Let $ABDC$ and $EFHG$ be two parallelograms with the same angles, which share a diagonal.


 * ComplementsOfParallelograms.png

Then the two parallelograms $CIGK$ and $BJHL$ are known as the complements of the parallelograms $ABDC$ and $EFHG$.

Linguistic Note
In this context, the thing being completed is the large parallelogram $AIJF$.