If \( (\vec{a} + 3\vec{b}) \) is perpendicular to \( (7\vec{a} - 5\vec{b}) \) and \( (\vec{a} - 4\vec{b}) \) is perpendicular to \( (7\vec{a} - 2\vec{b}) \), then the angle between \( \vec{a} \) and \( \vec{b} \) (in degrees) is ________.
