Radius criteria - TNSB3

11.5 Radius Criteria

Given two points and a radius, there are four possible arcs. The program will determine what arc should be used based on the degrees they cover and the radius sign.

Supposing that you have an edge AB and a radius R, of the four possible solutions those which cover more than 180 degrees can be discarded. Of the two arcs that remain, if the radius is positive, the arc to the left of the AB segment will be used. If it is negative, the arc to the right of the heading is used.

Another way to see how the arc sign affects the program is that the positive values create arcs toward the outside of the section, whilst negative values create arcs toward the inside.

Figure 51 - Radius Sign Criteria