UNITAT 1: FORMES GEOMÈTRIQUES GEOMETRIC SHAPES

EDUCACIÓ VISUAL I PLÀSTICA – 1 ESO

Escola Betúlia - 2014 -2015

Chapter 1

Geometric Shapes

Polígon - Polygon

Side or edges

The segments are called sides or edges

The edges where two segments meet are the polygon’s vertices (sing vertex) or corners

vertex

Cambridge definition: a flat shape with three or more straight sides

Polygon

You can make names using this method:

 ...end with+1 ...henagon+2 ...digon+3 ...trigon+4 ...tetragon+5 ...pentagon+6 ...hexagon+7 ...heptagon+8 ...octagon+9

Start with...20  Icosi...30  Triaconta...40  Tetraconta...50  Pentaconta...60  Hexaconta...70  Heptaconta...80  Octaconta...90  Enneaconta...100 Hecta...etc..  

Example: a 63-sided polygon is a Hexacontadigon

BUT, for polygons with 13 or more sides, it is OK (and easier) to write "13-gon", "14-gon" ... "100-gon", etc.

Regular Polygon

Triangle

A plane figure with three straight sides and three angles

A triangle is a polygon with three edges and three vertices. It is one of the basic shapes in geometry.

Equilateral Isosceles Scalene

Quadrilateral

A quadrilateral is a polygon with four sides (or edges) and four vertices or corners.

Simple quadrilateral Complex quadrilateral

Quadrilateral

The interior angles of a simple (and planar) quadrilateral ABCD add up to 360 degrees of arc, that is

Pentagon

A pentagon is any five-sided polygon. A pentagon may be simple or self-intersecting. The sum of the internal angles in a simple pentagon is 540°.

A pentagram is an example of a self-intersecting pentagon.

A regular pentagon, all sides are equal in length and each interior angle is 108°

Polyhedron

A polyhedron (plural polyhedra or polyhedrons) is a solid in three dimensions with flat faces, straight edges and sharp corners or vertices (singular: vertex).

face

edge

Corner or vertex

Regular Polyhedron

Tetrahedron Hexahedron Octahedron Dodecahedron Icosahedron

3 faces 4 faces 8 faces 12 faces 20 faces

Known as the Platonic solids

Regular Polyhedron

Small stellated dodecahedron

Great dodecahedron

Great stellated dodecahedron

Great icosahedron

12 pentagrammic

faces

12 pentagonal faces 

12 intersecting pentagrammic faces

20 intersecting triangular faces

Known as the Kepler-Poinsot polyhedra

Pentagons in polyhedra

Dodecahedron Pyritohedron Pentagonal icositetrahedron

Pentagonal hexecontahedron

Truncated_trapezohedron

Archimedean solidAn Archimedean solid is a highly symmetric, semi-regular convex polyhedron composed of two or more types of regular polygons meeting in identical vertices

Truncated tetrahedron

Cuboctahedron Truncated hexahedron

Truncated octahedron

Small rhombicuboctahedron

Great rhombicuboctahedron

Snub hexahedron Icosidodecahedron Truncated

dodecahedronTruncated

icosahedron

4 triangles4 hexagons

8 triangles6 squares 8 triangles

6 octagons6 squares

8 hexagons

8 triangles18 squares

12 squares8 hexagons6 octagons

32 triangles6 squares

20 triangles12 pentagons 20 triangles

12 decagons12 pentagons20 hexagons

Archimedean solid

Small rhombicosidodecahedron

Great rhombicosidodecahedron

Snub dodecahedron

20 triangles30 squares

12 pentagons

30 squares20 hexagons12 decagons

8 triangles6 octagons