Circumcentre + Circumradius

    Vector3 GetCircumCentre(Vector3 a, Vector3 b, Vector3 c) {
        Vector3 p1 = (c - a).sqrMagnitude * Vector3.Cross (Vector3.Cross (c - a,b - a), b - a);
        Vector3 p2 = (b - a).sqrMagnitude * Vector3.Cross (Vector3.Cross (b - a, c - a), c - a);
        float div = 2 * Vector3.Cross (b - a, c - a).sqrMagnitude;
        Vector3 centre = a - (p1 + p2) / div;
        return centre;
    }

    float GetRadius(Vector3 a, Vector3 b, Vector3 c) {
        float lenA = Vector3.Distance (a, b);
        float lenB = Vector3.Distance (b, c);
        float lenC = Vector3.Distance (c, a);
        float s = (lenA + lenB + lenC) * .5f;
        return (lenA*lenB*lenC)/(4*Mathf.Sqrt(s*(lenA+lenB-s)*(lenA+lenC-s)*(lenB+lenC-s)));
    }