A squashed Astroid as an Envelope
In the applet below the radius of the orange circle is and the radius of the blue circle is . One point is moving clockwise along the blue circle and another point is moving counterclockwise along the orange circle. The envelope of the lines passing through these points is a squashed astroid.
- Drag the slider to change the radius of the blue circle.
- Show the graph of the (non-squashed) astroid.
- What happens when the radius increases?