Location of points by resection requires pointings made on at least :
- Aone known station
- Btwo known stations
- Cthree known stationsCorrect
- Dfour known stations
Solution
Concept
Resection
Step-by-step solution
1. In resection the position of an occupied station is found by sighting known stations. 2. Three known points are needed (three-point problem) for a unique solution.
Explanation
The three-point problem (Bessel's, Lehmann's, tracing paper method) locates the plane-table station from pointings on three known stations. Two known stations are used for two-point problems, which need an extra auxiliary station.
Why the other options are wrong
One station gives only a line. Two known stations are not enough without an extra point. Four stations are not needed.
Shortcut
Resection = 3 known points.
Common mistake
Choosing two stations.
Correct answer: C) three known stations