Thursday 5 January 2017

POLYGONS

Polygons 

(FROM: https://www.mathsisfun.com/geometry/polygons.html)

A polygon is a closed plane figure with 3 or more straight sides and angles. Examples include triangles, quadrilaterals, pentagons, hexagons and so on.
Polygon comes from Greek. Poly- means "many" and -gon means "angle".

Is it a Polygon?

Polygons are 2-dimensional shapes. They are made of straight lines, and the shape is "closed" (all the lines connect up).
pentagon irregular not a pentagon (curve) not a pentagon (open)
Polygon
(straight sides)
Not a Polygon
(has a curve)
Not a Polygon
(open, not closed)

Types of Polygons

Regular or Irregular

A regular polygon has all angles equal and all sides equal, otherwise it is irregular
pentagon regular pentagon irregular
Regular Irregular

Concave or Convex

A convex polygon has no angles pointing inwards. More precisely, no internal angle can be more than 180°.
If any internal angle is greater than 180° then the polygon is concave. (Think: concave has a "cave" in it)

Concave
Convex

Simple or Complex

A simple polygon has only one boundary, and it doesn't cross over itself. A complex polygon intersects itself! Many rules about polygons don't work when it is complex.


Simple

Complex



More Examples

hexagon irregular concave octagon star polygon
Irregular Hexagon Concave Octagon
Complex Polygon
(a "star polygon",
in this case a pentagram)


Names of Polygons



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