In triangle \( \triangle ABC \), \( AB = 7 \), \( BC = 24 \), and \( CA = 25 \). A circle is inscribed in the triangle, touching \( BC \) at point \( D \), \( CA \) at point \( E \), and \( AB \) at point \( F \). Calculate the radius of the inscribed circle. Let's think step by step and output the final answer within \boxed{}.
user