Three-Dimensional Solids
Three-dimensional Solids have dimensions in 3 directions - length, width and depth. In geometry, we are mainly interested in three types of 3D solids which are:
- Prism - where the cross-section has the same shape and the same size all the way along the object (e.g. cube, rectangular box, cylinder)
- Pyramid - where the cross-section has the same shape, but the cross-section reduces in size to a point (e.g. Egyptian pyramid, cone)
- Sphere - round object (e.g. basketball).
Prisms
| Cube (Square-based prism) |  |
| Rectangular Prism |  |
| Triangular Prism |  |
| Cylinder (Circle-based Prism) |  |
Question - Prisms in Gym Equipment
Look at the gym equipment. Identify 3 prisms.
Did You Know That...?
This triangular prism is dispersing white light into the seven light wavelengths of the visible light spectrum - red, orange, yellow, green, blue, indigo and violet. What we cannot see with our human eyes is the invisible light including radio waves, microwaves, infra-red, ultra-violet, x-rays and gamma-rays.
Pyramids
| Square-based pyramid |  |
| Tetrahedron (Triangle-based pyramid) |  |
| Cone (Circle-based pyramid) |  |
Did You Know That...?
Use a magnifying glass to look very closely at the salt in your kitchen. The crystals of table salt (also known as sodium chloride and halite) are in the shapes of cubes.
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