Given trapezoid KLMN, with KL // NM, KL = a, and NM = b.
Construct the midpoint of KN and call it point P. Construct the midpoint of LM and call it point Q.
Construct segment PQ. The length of this segment is the arithmetic mean, "A," of the bases KL and NM.
Double check the construction by taking measurements and using the equation for finding the arithmetic mean.
