Perimeter of Triangle
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Theorem
Let $ABC$ be a triangle.
Then the perimeter $P$ of $ABC$ is given by:
- $P = a + b + c$
where $a, b, c$ are the lengths of the sides of $ABC$.
Proof
The perimeter of a plane geometric figure is defined as the total length of the boundary.
By definition, the boundary of a triangle comprises the three sides of that triangle.
Hence the result.
$\blacksquare$
Sources
- 1968: Murray R. Spiegel: Mathematical Handbook of Formulas and Tables ... (previous) ... (next): $\S 4$: Geometric Formulas: $4.6$