_______ is the method of locating an offset point from 2 different points on a chain line in such a way that all the three points form a near-equilateral triangle.
- ASwing offset method
- BPerpendicular offset method
- COblique offset method
- DMethod of tiesCorrect
Solution
Concept
In the method of ties, a point is fixed by measuring its distance from two known points on the chain line, so the three points form a well-conditioned (near-equilateral) triangle.
Step-by-step solution
1. The question asks how to fix a point from two different points on the chain line. 2. Measuring two distances from two chain line points to the object is called locating by ties (tie measurements). 3. A good triangle has angles close to 60°, so it is near-equilateral. 4. So the answer is Method of ties.
Explanation
In the method of ties, we take two points on the chain line and measure their distances to the object. The three points form a triangle. If this triangle is near-equilateral, it is well-conditioned and the point is fixed accurately.
Why the other options are wrong
A: A swing offset finds the perpendicular by swinging the tape from one point only. B: A perpendicular offset is one measurement at 90° from one point. C: An oblique offset is one measurement at an angle other than 90°, not a triangle from two points.
Shortcut
Two points on the chain line plus a near-equilateral triangle means ties.
Common mistake
Choosing oblique offset because the measurements are not at 90°.
Correct answer: D) Method of ties