You can put this solution on YOUR website! ABCD is a rectangle
N is the mid point of CD
Therefore CN congruent to ND
In triangles
BCN & DAN
AD congruent to BC ( opposite sides of a rectangle)
angle BCN congruent to ADN = angle ( right angle of a rectangle)
CN congruent to DN ( given - N is the mid point of CD)
Therefore the triangles BCN & DAN are congruent by ( SAS test)
Therefore AN is congruent to BN