đường tròn

Etymology
.

Noun

 * 1)  a

Usage notes

 * Not to be confused with which is a shape that has a . A đường tròn only has a  (also known as a ), and can be described with an equation like other curves, such as the, ,  and . A similar distinction is made in 3D geometry, whereby, for example, a "" sphere has a , but a "" sphere only has a.