TITLE: How can I find the points at which two circles intersect?
QUESTION [55 upvotes]: Given the radius and $x,y$ coordinates of the center point of two circles how can I calculate their points of intersection if they have any?

REPLY [3 votes]: After going through most of the answers posted here, I still struggled implementing them.
After much searching around I found this page:
http://www.ambrsoft.com/TrigoCalc/Circles2/circle2intersection/CircleCircleIntersection.htm
It includes extensive notation on every part of the equation as well as drawings, a calculator and JavaScript implementation.
Hope it can help others.