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Radians

Maths: Edexcel A Level Pure Maths, topic 5.1.1

Radians

A radian is another unit for measuring angles. There are 2π2\pi radians in a full circle. The radian unit can be written as rad.

Definition of a radian

Definition of a radian

  • The angle between two radii of a circle connected by an arc length that is equal in length to the radius is equal to one radian.
Comparison to degrees

Comparison to degrees

  • There are 2π\pi radians and 360 degrees in a circle.
  • If an object travels all the way around a circle it has done one revolution.
  • 1 rad=3602π≈57.3o1\text{ rad}=\frac{360}{2\pi} \approx 57.3^o

Test yourself on Radians

  • How many radians make a full circle?

  • What is π radians in degrees?

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