What rights do I have to view a trust document since there is no will?

My father left a building and bank account in a trust and named my brother as trustee. It was meant to care for our mother. She passed away in March of this year. I have not seen the trust document, but my brother says there is nothing in the bank account and that the building was left to him and is not part of my mother's estate. Her house and car were not included in the trust, so they will be sold and divided between my brother, sister, and I. There is no will. How do I protect my rights in this situation. If my sister and I are not beneficiaries of the trust, then I suppose that's that, but I don't know this for sure.