UNIT 7

UNIT 7

1. 2.2.1 Three-Dimensional forms: width,height and depth.

2. Polyhedra and Platonic Solids

   • Solids have properties
   • Volume
   • surface area
   • how many vertices
   • The sides of a polyhedron are called faces, the lines where faces meet are called edges, and the corners where edges meet are called vertices.

3. Tetrahedron: A 4-faced polyhedron and all the faces are equilateral triangles. / Hexahedron or cube: A 6-faced polyhedron and all the faces are squares. Octahedron: An 8-faced polyhedron and all the faces are equilateral triangles. Dodecahedron: A 12-faced polyhedron and all the faces are regular pentagons. Icosahedron: A 20-faced polyhedron and all the faces are equilateral triangles.

4. Non Polyhedra

   • Sphere: • It is perfectly symmetrical • All points on the surface are the same distance "r" from the center • It has no edges or vertices (corners) • It has one Surface
   • Cylinder • It has a flat base and aflat top • The base is the same as the top • From base to top the shape stays the same • It has one curved side
   • Cone • It has one curved side • The pointy end of a cone is called the apex • The flat part is the base
   • Torus • it can be made by revolving a small circle (radius r) along a line made by a bigger circle (radius R). • It has no edges or vertices

Images and files in the map