Nets Slideshow 45, Mathematics Mr Richard Sasaki Room 307
Objectives Recall names of some common 3d Shapes Understand how nets are formed Be able to build nets for different shapes (Please bring some scissors and glue for next lesson!)
Some Simple 3-D Shapes Cylinder Cone Sphere Square-based pyramid Hemisphere
Platonic solids / conVEXregular polyhedrons Cube Tetrahedron Octahedron Dodecahedron Icosahedron
Prisms Triangular Prism Cuboid Hexagonal Prism Pentagonal Prism Octagonal Prism Decagonal Prism Dodecagonal Prism Heptagonal Prism
Nets A net is an unfolded 3D shape laid flat (in 3D). Nets are usually made for polyhedrons. What is a net? A net also makes it easy for us to see how many faces a shape has. Stating how many edges or vertices might be harder though.
Net – Cube There are many ways to unfold the cube (or any 3D shape) but the most common is… If this is rotated or flipped, it is still the same net. How many nets for the cube are there?
Making Nets x We don’t usually need to draw these though. o x o x If we make a net, we need flaps to glue, like this… o What edge will the flap marked touch? Try the next worksheets!
Answers - Easy Tetrahedron, Cuboid (Rectangular Prism), Cylinder Cylinder iv. Tetrahedron ii. Cuboid v. Tetrahedron iii. Cuboid vi. Cuboid
Answers - Medium 1. Triangular Prism, Pentagonal Prism, Octagonal Prism, Hexagonal Based Pyramid b. Pentagonal Prism ii. Hexagonal Based Pyramid iii. Octagonal Prism 2. Each circular face is connected to another face by a point (with 0 length and width).
Answers - Hard Octahedron c. 8 faces, 6 vertices d. 12 edges 2. Two faces will be on the same side of the “bunch”/ group. 3. V = 2F – 4 (Difficult question, well done if you got this!)