The three poles <b>P</b><sub>1–3</sub> of the radical axis <i>R</i> in the three given circles provide the second point needed to draw lines <i>L</i><sub>1–3</sub>
<a href="//commons.wikimedia.org/wiki/User:WillowW" title="User:WillowW">WillowW</a>
CC BY 3.0
<span class="int-own-work" lang="en">Own work</span>