The Radius of an Excircle. Let a Triangle have exradius (sometimes denoted ),
opposite side and angle , Area , and Semiperimeter . Then
(1) | |||
(2) | |||
(3) |
(4) |
(5) |
(6) |
(7) |
(8) |
(9) |
(10) |
(11) |
See also Circle, Circumradius, Excircle, Inradius, Radius
References
Johnson, R. A. Modern Geometry: An Elementary Treatise on the Geometry of the Triangle and the Circle. Boston, MA:
Houghton Mifflin, 1929.
Mackay, J. S. ``Formulas Connected with the Radii of the Incircle and Excircles of a Triangle.''
Proc. Edinburgh Math. Soc. 12, 86-105.
Mackay, J. S. ``Formulas Connected with the Radii of the Incircle and Excircles of a Triangle.''
Proc. Edinburgh Math. Soc. 13, 103-104.
© 1996-9 Eric W. Weisstein