This personal site from Math2.org gives formulas for the area, volumes and surface areas of various shapes. Also provides diagrams.

A population map of United States and territories in 1820 showing the distribution of the European-American population at the time and the general tribal lands of the Native Americans east of the Mississippi River. The map shows the...

A population map of United States and territories in 1820 showing the distribution of the European-American population at the time and the general tribal lands of the Native Americans east of the Mississippi River. The map shows the...

A population map of United States and territories in 1830 showing the distribution of the European-American population at the time and the general tribal lands of the Native Americans east of the Mississippi River. The map shows the...

A map from 1916 of Europe showing the population density of the region at the time. This map is keyed to show areas of population densities ranging from under 2 inhabitants per square mile to areas of over 512 inhabitants per square mile.

A map from 1915 of Africa and Madagascar showing the population density of the region at the time. This map is keyed to show areas of population densities ranging from under 2 inhabitants per square mile to areas of over 512 inhabitants...

A map from 1915 of Australia showing the population density of the region at the time. This map is keyed to show areas of population densities ranging from under 2 inhabitants per square mile to areas of over 128 inhabitants per square...

A map of the original thirteen States in 1790 showing State lines, territories northwest and south of the Ohio River, British and Spanish possessions, and the distribution of the European-American population east of the Mississippi River...

A map from 1910 showing the political boundaries and the distribution of population density of Asia at the time. This map uses gradated shading to shows areas of population densities ranging from under 2 inhabitants per square mile to...

A map from 1911 of South America showing the population density across the region. The map is color-coded to show areas of population densities ranging from under 2 persons per square mile to over 256 persons per square mile. A chart at...

A map of the United States showing the distribution of the population in 1880. The map is keyed to show areas of population with densities ranging from under 2 inhabitants per square mile to 90 and over inhabitants per square mile.

A map from 1919 of the railways networks in Asia at the time, showing trunk or main railways with heavy black lines, and lesser railways with lighter lines. A chart at the bottom of the map shows a comparison of the number of square...

"The city [Mexico City] is in what is called the Federal District, covering an area of some four hundred and fifty square miles - the government of the district like the District of Columbia is directed, by the national legislature,...

This site explores the area of congruent triangles and how it is a difficult area to understand.

A map from 1916 of North America, Central America, Greenland, and the Caribbean to Puerto Rico showing the population distribution at the time. The map is color-coded to show areas where the population density ranges from under 1...

A map from 1910 of population density in Europe, keyed to show area density ranges from under 2 to over 512 inhabitants per square mile, and cities with over 500,000 inhabitants.

A map of the central and eastern United States in 1860 showing the distribution of the population in the region at the time. The map shows State lines, the frontier line in 1860, and is keyed to show the areas of population density...

A map from 1912 of the United States, subtitled "Distribution of Population and Railways in 1850." The map is color-coded to show population densities ranging from areas with fewer than 2 inhabitants per square mile to areas of 90 or...

A map of the eastern United States in 1790 showing the western extent of the territories to the Mississippi, and the distribution of European-American population at the time. The map is keyed to show areas of population densities ranging...

A map of the central and eastern United States in 1840 showing the distribution of the population in the region at the time. The map shows State lines, the frontier line in 1840, and is keyed to show the areas of population density...

A map from 1907 of the United States showing the distribution of the population in 1870. The map is keyed to show areas of population with densities ranging from under 2 inhabitants per square mile to 90 and over inhabitants per square...

A map from 1912 of the United States, subtitled "Distribution of Population and Railways in 1900" showing the increase in population and expansion of the railroad network since 1850. The map is color-coded to show population densities...

A map of the United States showing the distribution of the population in 1910. The map is keyed to show areas of population with densities ranging from under 2 inhabitants per square mile to 90 and over inhabitants per square mile. The...

A map of the original thirteen States in 1790 showing the distribution of the European-American population at the time and the general tribal lands of the Native Americans east of the Mississippi River. The map shows the State lines,...