Radius

Type:: float, or section
Range:: [-inf, inf]
Default:: -/-
Appearance:: optional
Excludes:: Sagitta

Specifies the signed radius $R$ of the circle containing the arc. Its sign selects the side on which the arc bulges, as described in Arc; its magnitude is the circle radius.

For a chord of length $L$ , a valid radius satisfies

$\begin{eqnarray*} |R| \geq \frac{L}{2}. \end{eqnarray*}$

Equality produces a semicircle. Increasing $|R|$ produces a shallower arc. A zero radius is invalid. Radius and Sagitta are mutually exclusive.