[alogo] Link-point locus

Consider two fixed circles b, c and a fixed segment of length d.
1) Set a point B on b, draw circle with center at B, radius = d.
2) Let C be one intersection-point of that circle with c, so that BC = d.
3) Set a point A on BC.
4) We want the path of A, as B moves on circle b.

Choose the geometric-locus (CTRL + 3) and click at B and A.
This creates the geometric-locus of A (red curve).

Choose the pick-move tool (CTRL + 2), catch and move A along BC, to see how the
locus (red) varies, depending on the location of A.
- For A near B it is almost identical with circle b,
- For A near C it is almsot identical with a circle arc of c.

[0_0] [0_1] [0_2]
[1_0] [1_1] [1_2]

BC is the middle link of a 3-link gear system.
There are critical sizes of d, which make the system collapse.
When d is too small or too big.
The system has a normal behaviour only for values
X <= d <= Y . For certain constants: X, Y, depending on the two circles and their position.

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