Monday, July 11, 2011

Cuboids, Rectangular Prisms and Cubes

A cuboid is a box-shaped object.

It has six flat sides and all angles are right angles.

And all of its faces are rectangles.

It is also a prism because it has the same cross-section along a length. In fact it is a rectangular prism.

Examples of Cuboids

Cuboids are very common in our world, from boxes to buildings we see them everywhere. You can even fit them inside other cuboids!

A box with a slot cut as a handle Cuboids in a cuboid room Boxes for model trains Now that's just silly!

Volume and Surface Area

The volume of a cuboid is found using the formula:

Volume = Height × Width × Length

Which is usually shortened to:

V = h × w × l

Or more simply:

V = hwl

The volume of the following solids are often required to solve real world problems involving quantity, capacity, mass and strength of materials including liquids.

Volume of a Cube

Example 25

Find the volume of a cube of side 4 cm.


Solution:


Surface Area

And the surface area is found using the formula:

A = 2wl + 2lh + 2hw

Example: Find the volume and surface area of this cuboid.


V = 4×5×10 = 200

A = 2×4×5 + 2×5×10 + 2×10×4
= 40+100+80 = 220

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