Surface Area of Cuboid
Theorem
Let $\CC$ be a cuboid whose edges are of length $a$, $b$ and $c$.
The surface area $S$ of $\CC$ is given as:
- $S = 2 \paren {a b + b c + a c}$
Proof
Each of the faces of $\CC$ are rectangles:
- $2$ of these faces are adjacent to edges of length $a$ and $b$
- $2$ of these faces are adjacent to edges of length $b$ and $c$
- $2$ of these faces are adjacent to edges of length $a$ and $c$.
Hence from Area of Rectangle:
- there are $2$ faces with area $a b$
- there are $2$ faces with area $a c$
- there are $2$ faces with area $b c$.
Hence the result.
$\blacksquare$
Sources
- 1968: Murray R. Spiegel: Mathematical Handbook of Formulas and Tables ... (previous) ... (next): $\S 4$: Geometric Formulas: Rectangular Parallelepiped of Length $a$, Height $l$, Width $c$: $4.27$
- 1998: David Nelson: The Penguin Dictionary of Mathematics (2nd ed.) ... (previous) ... (next): parallelepiped
- 2008: David Nelson: The Penguin Dictionary of Mathematics (4th ed.) ... (previous) ... (next): parallelepiped
- 2009: Murray R. Spiegel, Seymour Lipschutz and John Liu: Mathematical Handbook of Formulas and Tables (3rd ed.) ... (previous) ... (next): $\S 7$: Geometric Formulas: Rectangular Parallelepiped of Length $a$, Height $b$, Width $c$: $7.27.$