A trapezoid midsegment connects the midpoints of the two congruent sides of the trapezoid, and is parallel to the pair of parallel sides. The length of the midsegment is the sum of the two bases divided by 2. Remember that the bases of a trapezoid are the two parallel sides.
Explanation: A midsegment of a triangle is a segment connecting the midpoints of two sides of a triangle. This segment has two special properties. It is always parallel to the third side, and the length of the midsegment is half the length of the third side.