# How to generate numbers from Beta distribution in R if one of the parameters is $\theta$?

I have to estimate ( using method of moments) $$\theta$$ with an estimator $$\hat{\theta}$$ for a function with pdf given as $$\theta x^{\theta-1}, \ \ \ \text{ for 0 < x < 1, and } 0 \ \text{ otherwise}$$.

I found that that the $$\hat{\theta} = \frac{\bar{x}}{1-\bar{x}}$$, but now I need to estimate the $$\theta$$ in program R.

So, first I define $$\theta$$ as follows: $$\hat{\theta} = function(sample) \{ rbeta(n = 100, shape1 = \theta, shape2 = 1 \}$$

Here I am already stuck, because I don't know the value of $$\theta$$? Maybe there is some known value used for parameter $$\alpha$$ in Beta distribution?