# Calculate intermediary control points in Cubic Bezier Curves

I need to programatically generate two-dimensional circles of various dimensions, knowing only their radius and position. The circles will be drawn by employing 4 cubic Bezier curves. How should I calculate the Cartesian coordinates of the two intermediary control points of each arc?

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The control points between $(1,0)$ and $(0,1)$ are at $(1,k)$ and $(k,1)$ with $k=\frac43(\sqrt2-1)$.