This is the same situation as in the last problem. A midsegment in a triangle is a segment whose endpoints are the midpoints of two sides of the triangle. The midsegment is parallel to an half the length of the third side of the triangle.
Segment DE is half the length of segment AB.
We can use the coordinates of points A and B and the distance formula to find the length of segment AB. Then the length of segment DE is simply half the length of segment AB.







