What symbol represents the radian?
rad.
Are there any others?
yes
Are they frequently used?
no
Why?
but these symbols are infrequently used as it can be easily mistaken for a degree symbol (°) or a radius (r
What does the term describe?
the plane angle subtended by a circular arc
Is it used in many areas?
yes
What is equal to the measurement in radians?
The length of an arc of a unit circle
What was the units former classification?
an SI supplementary unit
Does that category still exist?
no
What happened to it?
it was abolished
When?
1995
What is the category it is in now?
an SI derived unit.
What is a steradian?
the SI unit of solid angle measurement