The th roots of unity are roots of the cyclotomic equation
which are known as the de Moivre numbers. The notations , , and are variously used to denote the th th root of unity.
is always an th root of unity, but -1 is such a root only if is even. In general, the roots of unity form a regular polygon with sides, and each vertex lies on the unit circle.
th roots of unity are roots 
of the cyclotomic equation 
,
, and 
are variously used to denote the 
th 
th root of unity. 
is always an 
th root of unity, but -1 is such a root only if 
is even. In general, the roots of unity form a regular polygon with 
sides, and each vertex lies on the unit circle.