i tried to copy <a href="//commons.wikimedia.org/wiki/User:Tosha" title="User:Tosha">Toshas</a> <a href="//commons.wikimedia.org/w/index.php?title=Eccentricity.png&amp;action=edit&amp;redlink=1" class="new" title="Eccentricity.png (page does not exist)">Eccentricity.png</a> and to add the cases when the focus is on the line (the plane goes through the vertex
<p><a href="//commons.wikimedia.org/wiki/User:Bohocmasni" title="User:Bohocmasni">Bohocmasni</a>
</p>
<a href="//commons.wikimedia.org/wiki/User:Tosha" title="User:Tosha">Tosha</a>
CC BY-SA 3.0
<p><span class="int-own-work" lang="en">Own work</span>
</p>
<a href="//commons.wikimedia.org/w/index.php?title=Eccentricity.png&amp;action=edit&amp;redlink=1" class="new" title="Eccentricity.png (page does not exist)">Eccentricity.png</a>