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Head First 2D Geometry
book

Head First 2D Geometry

by Stray (Lindsey Fallow), Dawn Griffiths
November 2009
Beginner content levelBeginner
368 pages
8h 55m
English
O'Reilly Media, Inc.
Content preview from Head First 2D Geometry
186 Chapter 4
unusual centers
The center of a triangle can be outside the triangle
Triangle Centers Up Close
Obtuse
Right 90º
Equilateral 60º
Acute
Isoceles
Circumcenter
ORTHOCENTER CIRCUMCENTER
On the 90º
vertex
On the
midpoint of the
hypotenuse
Exterior
Exterior
Interior on altitude
in line with other
centers
Interior on altitude
Same as all other
centers
Same as all other
centers
The centroid
and incenter
are always
interior.
Inside the triangle
As crazy as it sounds, the circumcenter and orthocenter of a triangle can be
outside the triangle. This only happens if the triangle is obtuse (one angle
greater than 90º).
To draw the orthocenter
of an obtuse triangle you
have to extend the sides.
Orthocenter
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Publisher Resources

ISBN: 9780596808365Errata Page