Trilateration with 4 beacons?

Hello there, I have been looking for a trilateration algorithm for my school thesis considering having and I use Estimote beacons.
My undestanding is that for trilateration you need 3 beacons. However your Indoor Location App is working with 4+ beacons I am a bit confused. Do you trilaterate with the 4 beacons at the same time? How? Or do you use a trilateration of 3 beacons having the 4th beacon measurement to somehow correct the final result?

Could you explain which mathematical formulas do you use? Thank you for your response.

I’m afraid we can’t share the math behind Indoor Location. There’s plenty of trilateration examples on the Internet though, if you need a starting point for your thesis.

I can share with you some code that I used to trilateration using any number of points, this would be just sample code used with my permission.