Question 814507
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