random rotation on a 3d sphere given an angle

Adapted from Nice Schertler, this is the code I am using

    Vector3 GetRandomAroundSphere(float angleA, float angleB, Vector3 aroundPosition)
    {
        Assert.IsTrue(angleA >= 0 && angleB >= 0 && angleA <= 180 && angleB <= 180, "Both angles should be[0, 180]");
        var v = Random.Range(0F, 1F);
        var a = Mathf.Cos(Mathf.Deg2Rad * angleA);
        var b = Mathf.Cos(Mathf.Deg2Rad * angleB);

        float azimuth = v * 2.0F * UnityEngine.Mathf.PI;
        float cosDistFromZenith = Random.Range(Mathf.Min(a, b), Mathf.Max(a, b));
        float sinDistFromZenith = UnityEngine.Mathf.Sqrt(1.0F - cosDistFromZenith * cosDistFromZenith);
        Vector3 pqr = new Vector3(UnityEngine.Mathf.Cos(azimuth) * sinDistFromZenith, UnityEngine.Mathf.Sin(azimuth) * sinDistFromZenith, cosDistFromZenith);
        Vector3 rAxis = aroundPosition; // Vector3.up when around zenith
        Vector3 pAxis = UnityEngine.Mathf.Abs(rAxis[0]) < 0.9 ? new Vector3(1F, 0F, 0F) : new Vector3(0F, 1F, 0F);
        Vector3 qAxis = Vector3.Normalize(Vector3.Cross(rAxis, pAxis));
        pAxis = Vector3.Cross(qAxis, rAxis);
        Vector3 position = pqr[0] * pAxis + pqr[1] * qAxis + pqr[2] * rAxis;
        return position;
    }