Solution :
Given that , the base lengths of a trapezoid are 11 cm and 17 cm.
The base of a trapezoid means the two parallel sides of the trapezoid.
A trapezoid midsegment connects the mid point of the congruent sides of the trapezoid and is parallel to the base .
The length of the midsegment is the sum of the length of two bases divided by two.
length of trapezoid midsegment =

Hence, The length of midsegment of trapezoid is 14.