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The $17$th letter of the Greek alphabet.

Minuscules: $\rho$ and $\varrho$
Majuscule: $\Rho$

The $\LaTeX$ code for \(\rho\) is \rho .
The $\LaTeX$ code for \(\varrho\) is \varrho .

The $\LaTeX$ code for \(\Rho\) is \Rho .



Used to denote the density of a given body:

$\rho = \dfrac m V$


Area Density


Used to denote the area density of a given two-dimensional body:

$\rho_A = \dfrac m A$


  • $m$ is the body's mass;
  • $A$ is the body's area.

The $\LaTeX$ code for \(\rho_A\) is \rho_A .

Right Regular Representation


Let $\left ({S, \circ}\right)$ be an algebraic structure.

The mapping $\rho_a: S \to S$ is defined as:

$\forall a \in S: \map {\rho_a} x = x \circ a$

This is known as the right regular representation of $\struct {S, \circ}$ with respect to $a$.

The $\LaTeX$ code for \(\rho_a\) is \rho_a .

Radius of Curvature

The radius of curvature of a curve $C$ at a point $P$ is defined as the reciprocal of the absolute value of its curvature:

$\rho = \dfrac 1 {\left\lvert{k}\right\rvert}$