# Questions on thin prism

1.the angles of thin prism are very small ,that's why the prism is always in the position of minimum deviation angle.
I don't understand this statement at all!!how to prove this?

the deviation angle in a thin prism depends upon the refractive index but It doesn't depend upon the angle of incidence because the prism is always in the position of minimun deviation angle.

I don't understand this either.