Say we have three stochastic variables defined as follows:

```
rho = NormalDistribution[rhom,sigmar];
beta = NormalDistribution[betam,sigmab];
alpha = NormalDistribution[alpham,sigmaa];
```

I would like to compute the central moments of the following vector containing functions of such variables:

```
ml={{rho/(Sqrt[1+Tan[alpha]^2+Tan[beta]^2]) Tan[alpha]},
    {rho/(Sqrt[1+Tan[alpha]^2+Tan[beta]^2]) Tan[beta]},
    {rho/(Sqrt[1+Tan[alpha]^2+Tan[beta]^2])}};
```

How can this task be fulfilled taking advantage of the definition of such `Distribution` objects?