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Degrees to Radians

Theory & Practice Questions.


Radian, a circle measure

One radian is the angle that an arc of 1 unit subtends at the centre of a circle of radius 1 unit.


Degrees to radians conversion:  1 degrees = π/180 radians


Radians and Degrees

π^c = 180° 

where π^c  = π  radians

Relationship between radian measure and degrees

Circumference of the circle with radius 1 unit is given by:

C = 2πr

= 2π(1)

= 2π


The arc length of the whole circle is .


There are radians in a whole circle.


But there are 360° in a whole circle (angle of revolution).

So 2π^c = 360°

π^c = 180°


Degrees To Radians

To change from degrees to radians: multiply by π/180

Note: Special measure you will use regularly include -


Practice Question


  1. Convert 150°  into radians.
  1. To convert degrees into radians:


150°=150 x π/180 radians


=150π/180 radians


 =5π/6 radians

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