The correct method employed by GPS (Global Positioning System) to find the location of a target is through the technique known as trilateration. Let's explore how this method works and why it is relevant:

1. Understanding Trilateration:
   • Trilateration is a method of determining the position of a point by measuring distances to it from known points.
   • For GPS, the known points are typically satellites orbiting the Earth.
   • Specifically, GPS uses the information from at least three different satellites to perform trilateration to determine the target location.
2. Mechanism:
   • Each satellite sends a signal indicating its position and the time the signal was transmitted.
   • The GPS receiver on the ground picks up these signals and calculates how far away each satellite is based on the time it took for the signals to arrive.
   • By using signals from at least three satellites, the receiver can compute its own location through trilateration.
3. Reasoning for the Correct Option:
   • The option states: "Trilateration method, which measures lengths of sides of triangle with target location as one of the heads of the triangle".
   • This description aligns with the trilateration process, as the GPS receiver forms the "triangle" with the satellite measurements to compute position.
4. Why Other Options are Incorrect:
   • Dilation Method: No such method is used in GPS for location determination.
   • Geostationary Satellite Measurement: GPS satellites are not geostationary; they orbit the Earth, providing global coverage.
   • Polar Satellite Measurement: Similarly, GPS satellites do not utilize polar orbits specifically for location determination. They form a specific constellation to provide accurate data.

In conclusion, the GPS system relies on the trilateration method to calculate precise locations on the Earth, confirming that the correct answer is the trilateration method.