To find the length of segment \(\overline{AC}\) in triangle \(\triangle ABC\), we first need the coordinates of points \(A\) and \(C\).
From the problem statement, we have:
- \(A\) is at the coordinates \(A(4, 2)\)
- \(C\) is at the coordinates \(C(0, 0)\)
We can calculate the length of segment \(\overline{AC}\) using the distance formula, which is given by:
\[ d = \sqrt{(x_2 - x_1)^2 + (y_2 - y_1)^2} \]
Substituting the coordinates of points \(A(4, 2)\) and \(C(0, 0)\) into the distance formula:
\[ d = \sqrt{(0 - 4)^2 + (0 - 2)^2} \] \[ d = \sqrt{(-4)^2 + (-2)^2} \] \[ d = \sqrt{16 + 4} \] \[ d = \sqrt{20} \] \[ d = 2\sqrt{5} \]
Thus, the length of segment \(\overline{AC}\) is \(\boxed{2\sqrt{5}}\).