# Which system of units does the unit 'degree' belong to?

Let us say that I would like to store latitudes and longitudes like this:

lat 35 degree

long 80 degree

Which system of units does the unit 'degree' belong to? It is not really a SI unit nor a Imperial unit ...

• en.wikipedia.org/wiki/Angle#Units suggests degrees are derived from the SI derived unit Radians – Ian Turton Apr 24 '15 at 10:59
• First i removed, then added back the 'vector' tag back since a unit vector is an alternate means of storing angles. – Martin F Apr 24 '15 at 15:46

Degrees are part of a modified Sexagesimal (base 60) number system. Even though there are 360 degrees in a circle, 360 is 6 x 60. The origin of degrees as angular units is unclear (see wiki/Degree_(angle)#History.)

See Coordinate Conversion: Decimal Degree to Deg-Min-Sec of lat/long Coordinates for subdivisions of a degree.

In terms of fundamental physical units, mass, length and time, angles are actually unitless because they are derived from ratios of lengths:

For a sector: arc angle = arc length / radius

For a right triangle: angle
= arcsine (opposite / hypotenuse)