What is the fundamental unit used for an angle?

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justaguide | College Teacher | (Level 2) Distinguished Educator

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In the SI system of units there are 7 fundamental units for weight, length, luminous intensity, time, current, temperature, and amount of a substance.

These are expressed in kilogram, meter, candela, second, ampere, Kelvin, and mole.

All other quantities can be expressed using different combinations of the fundamental units.

There is no unit for an angle. The angle in a circle is taken to be a constant which could be either 360 degrees, or 2*pi radians, and any other angle can be expressed as a fraction of this. Doing this makes an angle a dimensionless quantity that is a number and a suffix is only required to state if the base angle was taken as 360 or 2*pi.