Assslam io alikum

Sir, Actually i am doing project  RF RANGE FINDER which will calculate the location and direction of FM radio station only within certain range u can say if device is placed in ur islamic university it will tell us location and direction of FM radiostation from my device.It is hardware based project and interfacing on Laptop

 

Now

I knew the three different physical path of certain FM radio station from my device.Now how i will determine the point of intersection of these three physical paths by using trilateration equations.(Three paths are must be taken by placing our device at three different points because we are using trilateration).

& what will be the minimum distance between two points (i.e device location ) 

Which trilatertion equation help me in calculating my cyclic error.