Curve as Envelope of Lines

 
1. Construct the astroid.
2. Construct the astroid as envelope of lines.
3. Construct the deltoid this way.
4. Construct the cardioid as thus:
5. Construct the nephroid as thus:
6. Draw this "star-shaped" curve:
7. Construct the deltoid as envelope of lines as thus:
8. Construct the astroid as envelope of lines as thus:
9. Construct the ellipse and the hyperbola as envelope of lines.