For first-order geodetic control, the average triangle closure should be which value?

For first-order geodetic control, the average triangle closure should be which value?

• A. 1.0 arcseconds
• B. 3 arcseconds
• C. 5 arcseconds
• D. 10 arcseconds

Answer: (A)

Triangle closure error is the difference between the sum of the measured angles in a triangle and the theoretical 180 degrees. In first-order geodetic control, angle measurements are extremely precise, and after adjustment the average angular misclosure per triangle is about 1 arcsecond. This tiny value shows the network is internally consistent and well tied to the reference frame. Larger misclosures, like a few arcseconds or more, would indicate less precision or issues needing re-measurement or re-adjustment. Therefore, the expected value for first-order control is around 1 arcsecond.

Triangle closure error is the difference between the sum of the measured angles in a triangle and the theoretical 180 degrees. In first-order geodetic control, angle measurements are extremely precise, and after adjustment the average angular misclosure per triangle is about 1 arcsecond. This tiny value shows the network is internally consistent and well tied to the reference frame. Larger misclosures, like a few arcseconds or more, would indicate less precision or issues needing re-measurement or re-adjustment. Therefore, the expected value for first-order control is around 1 arcsecond.