trilateration

Trilateration using 3 latitude and longitude points, and 3 distances

There exists an unknown target location (latitude and longitude co-ordinates). I have 3 latitude and longitude co-ordinate pairs and for each pair a distance in kilometers to the target location. How can I calculate the co-ordinates of the target location? For example, say I have the following data points 37.418436,-121.963477 0.2657...

Trilateration in a 2D plane with signal strengths

Hi, first question to StackOverflow, please be gentle. I am trying to find the equation (and then the algorithm for) the center point of three different points on a 2D cartesian plane, given a certain magnitude or "signal strength". These signal strengths are all on a scale relative to each other, but shouldn't necessary be conflated ...