 Encyclopedia of Triangle Centers  Clark Kimberling
A searchable catalogue of hundreds of special triangle points (centroid, incenter, Hofstadter points, Yff centers, Apollonius point, etc.), with a glossary, collinearities, graphics, and links to biographical sketches of geometers, geometry software and sites, and more. For pictures and constructions of selected cases, see Triangle Centers.
more>>
 Geometric Formulas (Ask Dr. Math FAQ)  Math Forum
Formulas for twodimensional figures: triangle (equilateral, isosceles, right, scalene); quadrilateral (general, square, rectangle, parallelogram, rhombus, trapezoid, kite, cyclic and cyclicinscriptable); regular polygon; circle (arc, segment, sector); ellipse; parabolic segment; and threedimensional figures: rectangular parallelepiped (cube); prism; pyramid (square pyramid, frustum); regular polyhedron (tetrahedron, cube, octahedron, dodecahedron, icosahedron); cylinder (right circular); cone (right circular, frustum); sphere (sector, cap, segment, zone, lune); ellipsoid; circular torus; spherical polygon. Includes Defining Geometric Figures.
more>>
 Mrs. Glosser's Math Goodies  Gisele Glosser
Interactive math lessons that work online and offline in a Web browser, and provide immediate feedback to students, with in addition Worksheets (on circumference and area; exponents; expressions and equations; integers; Ocean Math; order of operations; percent; perimeter and area; probability; and statistics), Math Chat Boards, Math Puzzles, a Math Image Library, Educational Links, Homework Suggestions, and more. Lessons include examples, exercises, and solutions. Volumes include: Introduction to Statistics; Topics in PreAlgebra; Probability Lessons; Integers; Understanding Percent; Number Theory; Circumference and Area of Circles; Perimeter and Area of Polygons; and Solutions. These math lessons are shareware and may be used online; registered users may save them to their desktop computers. Leçons en français are also available in French: Théorie des nombres; Circonférence et aire des circles; et Périmètre et aire des polygones.
more>>
 Naming Polygons and Polyhedra  Math Forum, Ask Dr. Math FAQ
What do you call an 11sided polygon? A 14sided polygon? Is there a list of names of polygons? What about polyhedra?
more>>
 The Pythagorean Theorem  Math Forum, Ask Dr. Math FAQ
What is the Pythagorean theorem? When would you use it? How can we prove it?
more>>
 Quadrilateral Formulas (Ask Dr. Math FAQ)  Math Forum
Formulas for finding the area, perimeter, etc. of a quadrilateral: square, rectangle, parallelogram, rhombus, trapezoid, trapezium, kite, and cyclic quadrilateral.
more>>
 Regular Polygon Formulas (Ask Dr. Math FAQ)  Math Forum
Formulas for finding the area, perimeter, etc. of a regular polygon, and constructing regular polygons with compass and straightedge, in particular the pentagon.
more>>
 Triangle Centers  Clark Kimberling; Dept. of Mathematics, Univ. of Evansville, Evansville, IN
A listing, with description and illustration, of 20thcentury triangle centers (including: Schiffler Point, Exeter Point, Parry Point, congruent isoscelizers point, Yff Center of Congruence, isoperimetric point and equal detour point, AjimaMalfatti Points, Apollonius Point, Morley Centers, Hofstadter Points, and equal parallelians points) and some classical triangle centers (including: centroid, incenter, circumcenter, orthocenter, Fermat Point, ninepoint center, symmedian (or Lemoine) point, Gergonne point, Nagel point, Mittenpunkt, Spieker center, Feuerbach point, isodynamic points, and Napoleon points), as well as other references (to print works) and a list of journals that frequently publish items of interest to triangle geometers.
more>>
 Triangle Formulas (Ask Dr. Math FAQ)  Math Forum
Formulas for finding the area, perimeter, etc. of an equilateral, isosceles, right, or scalene triangle.
more>>
 
