For first-order triangulation, the strength of figure R (between bases) should not exceed which value?

• A. 25
• B. 15
• C. 20
• D. 30

Answer: (A)

In triangulation, the figure strength between bases measures how well the geometry can carry and limit errors during adjustment. For first-order work, you want that geometry to be robust enough to prevent excessive error transfer, so the maximum allowable strength between the bases is set at 25. Keeping figure R at or below this value ensures the network remains well-conditioned and within the first-order accuracy requirements. If the strength were higher, errors could propagate more freely and degrade accuracy; the other numbers either impose too strict or different-order criteria, so they don’t apply to this specific first-order between-bases situation.