As other said it's not possible with polynomial curves, but you can get good approximation. Only rational curves can form arcs. Wikipedia has a nice explanatio

As other said it's not possible with polynomial curves, but you can get good approximation. Only rational curves can form arcs. Wikipedia has a nice explanation https://en.wikipedia.org/wiki/Non-uniform_rational_B-spline#Example:_a_circle https://en.wikipedia.org/wiki/Non-uniform_rational_B-spline#...