# Villalpando's proportionatrix secunda

Construction of the

*proportionatrix secunda*in a semicircle of diameter AG. Steps to find a point K of the curve from a point F of the semicircle:- Semicircle of diameter AG and center D(diagram).
- Semicircle of diameter DG.
- A point F is selected on the large semicircle, FG is drawn cutting the small semicircle in H.
- Perpendicular HI from H to AG.
- Semicircle of center I and radius IG.
- K is the intersection of this semicircle with FG.
- L is the intersection of this semicircle with AG. FL is drawn.

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