Definition:Excircle of Triangle/Exradius

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Definition

Excircle-of-Triangle.png


A radius of an excircle of a triangle is called an exradius of the triangle.

In the above diagram, $r_a$ is the exradius of $\triangle ABC$ with respect to $a$.


Also known as

An exradius is also known as an eradius.

Some (usually older) sources hyphenate: ex-radius.


Also see

  • Results about exradii of triangles can be found here.


Linguistic Note

The plural form of exradius is exradii.

Similarly, the plural form of eradius is eradii.


Sources