# Limaçons as Envelopes of Circles

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A limaçon can be defined as the envelope of the circles that pass through a fixed point P and have centers on a given circle . In this Demonstration, P is the origin. You can vary the center of the circle (shown in red) to see the envelope (shown in blue) change. Unchecking the "show limaçon" checkbox lets you picture the envelope on your own.

Contributed by: Daniel Joseph (March 2011)

Open content licensed under CC BY-NC-SA

## Snapshots

## Details

Snapshot 1: when P is at center of the circle , the envelope is a circle

Snapshot 2: when P is in the interior of but not at its center, the envelope is a dimpled limaçon

Snapshot 3: when P is on , the envelope is a cardioid

Snapshot 4: when P is outside of , the envelope is a limaçon with an interior loop

## Permanent Citation