3D geomatic point calculation

I have two questions.

1. I have three sensors in 3D measuring distance of one single target point. I know the sensor location in 3D and all distances between them and target. How can i find the unknown point? ( I got three circle euqtion, which doesn't make sense to solve?)
2. It is the inverse of the above question. I know the target point in 3D and all distanctes for 3 sensors. I know relative distance between three sensor also. How can i find the position of开发者_运维问答 this three sensors. I can have multiple target points with known distances.

There is an equation for the 3-D, three-point case at http://en.wikipedia.org/wiki/Trilateration; I think http://en.wikipedia.org/wiki/Multilateration answers the inverse question you posted.