Basic Guidelines For English Spellings

READ THESE ARTICLES## pentagon^{1}

### noun

A plane figure with five straight sides and five angles.

*‘In the second case, if the convex polygon is a pentagon incorporating all five points, then any four of these points can be connected to form a quadrilateral.’**‘This says that the most stable arrangement is a pentagon surrounded by five hexagons.’**‘The hexagons, pentagons, and triangles that make up the biomes all have their own unique specification due to the irregular nature of the site.’**‘Father entered the room, arms full of suitcases shaped in rectangles, pentagons, squares, and even spheres.’**‘You may know about a pentagon, a hexagon, or an octagon.’**‘He calculates the side of a regular pentagon in terms of the radius of the circumscribed circle.’**‘For those who don't know, a buckyball is an extremely stable soccer-ball-shaped molecule made up of 20 hexagons and 12 pentagons.’**‘Perfect crystal structures can contain pyramids, cubes, or hexagons, but not pentagons.’**‘The balls are made with small pieces of wood 12 pentagons and 20 hexagons which fit together to form a sphere.’**‘They are formed from 60 atoms of carbon bonded together in a combination of pentagons and hexagons to form a ball, just like a soccer ball.’**‘Thus, you can readily obtain a curved pentagon, heptagon, and so on.’**‘Similarly, nine atoms can form a pentagon bonded to a hexagon, each ring sharing two atoms with the other ring.’**‘When I looked at what she was doing, she was trying to work out (on the napkin) how to calculate the sum of the internal angles of a pentagon.’**‘Of course, this statement has to be explained, since it is untrue if we understand distance in the usual way: the edges of these pentagons are visibly not straight and do not have the same length.’**‘In plan, the building is comprised of five concentric pentagons, known as rings.’**‘There are 24 ways to do it - make 12 pentagons, so that the mirror images are on each side of the pentagon.’**‘Write the number 1 through 10 in the boxes below so each side of the pentagon has a sum of 14.’**‘Although it is impossible to inscribe a regular pentagon in a square, an equilateral pentagon can be inscribed in two ways.’**‘They are marked by a pentagon with three overlapping triangles.’**‘Analysts also use a variety of symbols, such as parallelograms, pentagons, and others, to depict different types of events and activities.’*

**Origin**

Late 16th century via Latin from Greek pentagōnon, neuter (used as a noun) of pentagōnos ‘five-angled’.

**Pronunciation**

## Pentagon^{2}

### proper noun

**the Pentagon**

1The pentagonal building serving as the headquarters of the US Department of Defense, near Washington, DC.

- 1.1The US Department of Defense.
*‘the Pentagon said 19 of its soldiers had been killed’*

- 1.1The US Department of Defense.

**Pronunciation**

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