P/S: The engine I work on doesn't have grouping integration. That's why I need a formula to change the position.
A and C are moving points that can move anywhere
A = (xa, ya), C = (xc, yc)
B (xb, yb) is a point between A and C colinearly
With one condition that distance of AB = constant = r, distance of AC can be varied.
How to find xb and yb?
Asked from Mathematics StackExchange:
The locus of all possible points B is a circle centred on A and of radius r. The intersection between this circle and line AC will give you point B (and another point opposite it on the circle which you can neglect).
Try to write down the relevant equations and solve them?