2
$\begingroup$

Given three identical circles, with three points of intersection. The line between two of these intersecting points is $3$ feet. They are inside a $4$th circle. All circles are tangent to each other.

What is the area of the $4$th circle? I don't understand if any of the Descartes Theorem or Three Tangent Circles applies and how.

Or perhaps more simply, if the "outer Soddy circle" equation will yield the needed answer. works

  • 0
    You can try getting the length from the centroid to a corner of the triangle formed by the centers of the three inner circles, and then add 3/2 to that to get the radius of the big circle.2011-05-02
  • 0
    Can you see that the distance between the intersections equals the radius of the equal circles?2011-05-02

2 Answers 2