a chord of a given length and passing a given point on the circle? just draw another circle centered at the point with the given radius, and use snap to intersection.
to draw a chord of a given length and passing a given point not on the circle:
1. draw a chord of the given length passing any point on the circle;
2. draw a concentric circle passing the point, and find the intersection with the chord;
3. rotate the chord to pass the given point: center of circle as the rotation center, the intersection point as the reference point.
How do you draw a chord of a given length? It seems if one end of a line is snapped to a circle it can't be rotated to snap the other end to the circle.
1/ Draw a horizontal (or angled) line of XX length with snap set as Middle on one of the quadrant points of circle.
2/ Draw vertical (or orthogonal) at each tip of tangent line crossing the circle.
3/ Chord of XX length is then shown in red.
Draw an auxiliary circle->Center,radius with radius set to the desired lenght and snap its center to the point in the base circle.
Draw a line line between the center of aux circle and any intersection between the aux circle and the base circle, it has the desired lenght and is a chord.
Remove aux circle, or draw another again if you want to continue drawing chords
Thank you all, that changed my perspective and is fit for purpose.
BTW, There still seems to be an issue with snap. The image below should show the chord on a 0.1m circle between the horizontal line and the intersection of the 7.75m circle. It snaps about 0.6mm off the intersection (suspiciously around the midpoint with the vertical offset).
In the quadrant points at 0°, 90°, 180° and 270° everything is fine, and it's worst at 45°, 135°, 225° and 315°.
It is nothing we can control from LibreCAD code. My assumption is, that the underlying graphics library uses some sine/cosine tables for performance reasons, which brings in the inaccuracy.
investing less than half an hour into Search function can save hours or days of waiting for a solution