# Niven's theorem

> The only rational angles in first quadrant whose sine is rational are 0, 30 and 90 degrees

**Wikidata**: [Q4116459](https://www.wikidata.org/wiki/Q4116459)  
**Wikipedia**: [English](https://en.wikipedia.org/wiki/Niven's_theorem)  
**Source**: https://4ort.xyz/entity/niven-s-theorem