To find the length of segment $DE$, we can use the midsegment theorem for triangles. This theorem states that the segment joining the midpoints of two sides of a triangle is parallel to the third side and is half as long as that side.

In this case, $DE$ is the midsegment connecting the midpoints of $AB$ and $BC$, so:

$DE = \frac{1}{2} \times AC$

Given that $AC = 8$ units, the length of $DE$ is:

$DE = \frac{1}{2} \times 8 = 4 \text{ units}$

The length of $DE$ is 4 units.

Would you like more details or have any other questions?

Here are 5 related questions for further exploration:

1. What are the properties of midsegments in different types of triangles?
2. How does the midsegment theorem apply to right triangles?
3. Can you find the perimeter of the triangle using the given information?
4. What is the area of triangle $ABC$?
5. How do the medians and midsegments of a triangle differ?

Tip: Midsegments divide triangles into smaller, similar triangles.