<P> The radian ( SI symbol rad ) is the SI unit for measuring angles , and is the standard unit of angular measure used in many areas of mathematics . The length of an arc of a unit circle is numerically equal to the measurement in radians of the angle that it subtends ; one radian is just under 57.3 degrees ( expansion at A072097 ) . The unit was formerly an SI supplementary unit , but this category was abolished in 1995 and the radian is now considered an SI derived unit . </P>
<P> The radian ( SI symbol rad ) is the SI unit for measuring angles , and is the standard unit of angular measure used in many areas of mathematics . The length of an arc of a unit circle is numerically equal to the measurement in radians of the angle that it subtends ; one radian is just under 57.3 degrees ( expansion at A072097 ) . The unit was formerly an SI supplementary unit , but this category was abolished in 1995 and the radian is now considered an SI derived unit . </P>
a radian is a measure of an angle that is approximately equal to
a radian is a measure of an angle that is approximately equal to
57.3 degrees
57.3 degrees