The <a href="https://en.wikipedia.org/wiki/Midsphere" class="extiw" title="en:Midsphere">midsphere</a> of a polyhedron. The red circles indicate the points at which a cone, with its apex at a vertex, is tangent to the sphere. Rendered in POV-ray based on a different rendering of the same model from D. Eppstein (2005), Quasiconvex programming, Combinatorial and Computational Geometry, Goodman, Pach, and Welzl, eds., MSRI Publications 52, 2005, pp. 287-331, arXiv:cs.CG/0412046.
<a href="//commons.wikimedia.org/wiki/User:David_Eppstein" class="mw-redirect" title="User:David Eppstein">David Eppstein</a>
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<span class="int-own-work" lang="en">Own work</span>