\textbf{25.} In a rhombus, the geometric mean of the two diagonals is the length of the rhombus's side. The smaller angle of the triangle formed by drawing the diagonals of this rhombus is how many degrees?
(1) $10$ \hspace{2cm} (2) $15$ \hspace{2cm} (3) $30$ \hspace{2cm} (4) $45$