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An 11sided polygon is called a hendecagon. It is also known as the undecagon or unidecagon. However, the term "hendecagon" takes precedence over these variants because of its consistency in using a Greek prefix and suff... More »
A 100sided polygon is called a hectogon, centagon or 100gon. In general, any nsided polygon with over 12 sides is called an ngon. While there are other conventions for naming polygons with any number of sides, it is ... More »
A sevensided polygon is called a "heptagon." "Hepta" or "hept" is a prefix from the Greek word meaning "seven." In addition to having seven sides, the heptagon also has seven angles where the sides meet. More »
An 11sided polygon is called a hendecagon. In order for an 11sided shape to be considered a hendecagon, its sides must all be straight and form a closed shape. More »
A decagon is a polygon that has 10 sides. Decagons can be both regular polygons, which have sides of equal length and equal interior angles between each side, or irregular polygons, which have unequal sides and angles be... More »
A polygon with five sides is called a pentagon. In Greek, "pente" means "five." When math textbooks discuss pentagons, they are typically referring to a polygon with five equal sides, otherwise known as a regular pentago... More »
Calculate the area of a trapezoid by identifying the length of the two parallel bases and the height of the polygon. Then, use the formula A = a + b/2 (h), where "a" and "b" are the two parallel base lengths and "h" refe... More »

US StandardsAligned
K12 Curriculum Aligned to Stateand Common Core Standards.

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