See also the Dr. Math FAQ: 3D and higher Browse Middle School
Two-Dimensional Geometry Stars indicate particularly interesting
answers or good places to begin browsing. Selected answers to
common questions: Pythagorean theorem proofs. - Euler's Formula
[11/26/2001] I have to find Euler's formula for two-dimensional
figures and explain it at a university level and at an
elementary-school level. - Figuring Out Formulas for Area
[08/24/1999] How can I remember formulas for squares, triangles,
cylinders, etc? - Figuring Square Footage and Yardage
[12/14/2002] What is the exact calculation used in order to
determine square footage or yardage of a given room? - Finding
Areas of Different Polygons [09/02/1997] Could you please tell
me how to work out the area for an equilateral heptagon,
octagon, nonagon, decagon, unedecagon, and dodecagon? - Finding
Captain Kidd's Treasure [05/17/2000] How can you find Captain
Kidd's treasure if you can't find the tree referenced in the
instructions? - Finding Line Segment Lengths