Which statement best describes the method used to determine position with two landmarks?

• A. Triangulation from ranges and bearings to two fixed landmarks.
• B. Averaging the distances.
• C. Using only one range value.
• D. Differentiating the ranges.

Answer: (A)

Two known landmarks let you fix your position by triangulation. Each landmark defines a locus where you could be based on what you measure to it. If you know the distance to each landmark, you can draw a circle around each landmark with that radius; your location is where those two circles intersect. If you know the direction (bearing) to each landmark, you can draw lines from each landmark along the reciprocal bearing; the intersection of those two lines gives your position. Often you’d use both ranges and bearings to get a more precise fix. With only one range, you’d be on a circle of possible positions, not a unique point, and averaging or differentiating ranges doesn’t provide a valid way to determine a single location. So using triangulation with ranges and bearings to two fixed landmarks yields the exact position.