About the Book
Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Pages: 70. Chapters: Triangle, Pythagorean triple, Law of sines, Nine-point circle, Altitude, Incircle and excircles of a triangle, Ceva's theorem, Orthocentric system, Right triangle, Pedal triangle, Triangle center, Law of cosines, Centroid, Fermat point, Mass point geometry, Heron's formula, Morley's trisector theorem, Johnson circles, Thales' theorem, List of triangle topics, Menelaus' theorem, Congruent number, Trilinear coordinates, Triangle strip, Euler line, Conway triangle notation, Inertia tensor of triangle, Simson line, Angle bisector theorem, Nagel point, Nine-point hyperbola, Exterior angle theorem, Weitzenbock's inequality, Stewart's theorem, Napoleon's theorem, Erd s-Mordell inequality, Medial triangle, Isogonal conjugate, Steiner-Lehmus theorem, Encyclopedia of Triangle Centers, Apollonius' theorem, Viviani's theorem, Symmedian, Semiperimeter, Schiffler point, Euler's theorem in geometry, One-seventh area triangle, Routh's theorem, Extouch triangle, Carnot's theorem, GEOS circle, Pedoe's inequality, Cevian, Hadwiger-Finsler inequality, Lester's theorem, Spieker circle, AA postulate, Pompeiu's theorem, Ono's inequality, Hinge theorem, Isodynamic point, CPCTC, Base, Saccheri-Legendre theorem, Marching triangles, SSS postulate, Barrow's inequality, Splitter, Triangular coordinates. Excerpt: A triangle is one of the basic shapes of geometry: a polygon with three corners or vertices and three sides or edges which are line segments. A triangle with vertices A, B, and C is denoted . In Euclidean geometry any three non-collinear points determine a unique triangle and a unique plane (i.e. a two-dimensional Euclidean space). Euler diagram of types of triangles, using the definition that isosceles triangles have at least 2 equal sides, i.e. equilateral triangles are isosceles. Triangles can be classified according to the relative ...
