Let $P$ and $Q$ be geometric figures of the same type (that is, having the same number and configuration of sides).
Let $A$ and $B$ be sides of $P$, and let $C$ and $D$ be sides of $Q$, such that $A$ and $C$ are corresponding sides, and $B$ and $D$ also be corresponding sides.
Then $P$ and $Q$ have sides which are in reciprocal proportion, or are reciprocally proportional, if:
- $A : D = B : C$
The definition of Reciprocally Related Figures:
- Two figures are reciprocally related when there are in each of the two figures antecedent and consequent ratios.