Wirebook › Glossary › Trilateration
What is trilateration?
In one sentence: Working out where something is from its distances to a few known points, where the circles (or spheres) around them meet.
A little more
If you know you're 5 km from one town, you could be anywhere on a circle around it. Add your distance from a second town and only two spots fit. A third distance leaves just one. That's trilateration: no angles needed, only distances.
GPS does it in three dimensions with spheres instead of circles, and uses one extra satellite to correct the receiver's clock, because the distances come from timing radio signals.
It's a bit like… Finding a friend at a festival when one person says "I'm 100 steps from the stage" and another says "50 steps from the food tent".