Math Forum Internet News

Volume 5, Number 23

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5 June 2000                                  Vol. 5, No. 23


        Encyclopedia of Triangle Centers - Kimberling
      Analytical Engine - Walker | Arithmetic - Banfill


A searchable catalogue of hundreds of special triangle 
points, including classical centers, points on Euler line,
isogonal conjugates of classical centers, centers on 
circumcircle, on nine-point circle, centers of central
triangles, isoscelizer centers, isoperimetric point, 
equal-detour point, Ajima-Malfatti points, Apollonius center, 
Ceva conjugates, isotomic conjugates, center of Parry circle, 
Morley centers, Hofstadter points, Kenmotu point, 
Yff-Malfatti point, Gossard perspector, centers on Euler 
line, Tixier points, center of Yiu conic, Eppstein points, 
Evans perspector, van Lamoen square-associated centers, 
centers on line at infinity, etc.

For pictures and constructions of selected cases, see 
Kimberling's Triangle Centers:



               THE ANALYTICAL ENGINE - John Walker


In the late 1800s, the mathematician Charles Babbage designed 
an Analytical Engine, a mechanical precursor to the computer. 
Read historical documents related to the Engine, including 
Blaise Pascal's account of his mechanical adding machine (in 
French), as well as Babbage's comments on designing ciphers. 

The site also allows you to run example programs, download
the Java source code, and explore a Java emulator of the 
Analytical Engine:



                   ARITHMETIC - John Banfill

Online interactive lessons, exercises, practice, and games
for grades K-8, designed to help students learn basic
arithmetic concepts and methods. 

Browse the table of contents, or use the Topic Index to find 
links to specific skill pages on addition, comparing 
quantities, counting, decimals, division, estimation, 
factors, fractions, money, multiplication, naming numbers, 
ordinal numbers, percent, place value, positions, properties, 
ratios, and subtraction.

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