The first construction multiplies the given angle by two.(Also known as Kempe's reversor).
The second construction extends the first, and shows how to multiply
a given angle by 3. He calls it a "multiplicator." It can
clearly be extended to multiply any given angle by a positive integer r.
Click on and drag the green point. The three angles incident to A are always equal to each other. (Again, the scale of the linkage can be adjusted by dragging point B.)
Created with Cinderella
Applets created by Dessislava Michaylova, modified by Michiko Charley