# Tusi couple

> mathematical device in which a small circle rotates inside a larger circle twice the diameter of the smaller circle

**Wikidata**: [Q1035674](https://www.wikidata.org/wiki/Q1035674)  
**Wikipedia**: [English](https://en.wikipedia.org/wiki/Tusi_couple)  
**Source**: https://4ort.xyz/entity/tusi-couple


## References

1. Freebase Data Dumps. 2013