Process Approach to Coin Dragon

The

The blue coin has to roll a distance equal to half its circumference about the red coin. Let's do this via a fictitious intermediate stage:

Roll the blue coin horizontally a distance of half of its circumference

Initial After Horizontal Roll-Out

Now wrap the roll-out about the red coin !!

Before the Wrap After the Wrap

Another way of describing this solution is that it is a two step solution

- Step 1: Top coin rolls horizontally the distance of half its circumference, turning thru' 180 degrees.
- Step 2: The horizontal "wrap" is wrapped around the static coin, with the coin attached,

For comparison, see