# Formula to calculate a position given three 2D locations and distance

I am doing a project for my final year computer science and normally post on stack-overflow but this question seems more suited for here. I need a formula to calculate my position from three 2D points and signal strength. I am pretty bad at maths and need a shove in the right direction.

An example of input would be,

Signal / Distance = -60 ([dBm][1]) , Co-ordinates [1.0,1.0]
Signal / Distance = -40 ([dBm][1]) , Co-ordinates [4.0,3.0]
Signal / Distance = -90 ([dBm][1]) , Co-ordinates [7.0,1.0]

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Can you convert signal strength to an absolute distance, or only to a relative one? You might look at the references in math.stackexchange.com/questions/39561/… – Ross Millikan Mar 4 '13 at 19:28
I'm using the Recieved Signal Strength Indicator (RSSI) which can vary due to obstacles. This question says more about getting the distance from RSSI. stackoverflow.com/questions/13705647/… I can only convert assuming there's nothing in the way.. – Tom celic Mar 4 '13 at 19:50