You are given a square abcd, and midpoints m and n are marked on bc and cd, respectively. draw am and bn, which meet at q. find the size of angle aqb.

Step 1: show triangles ABM and BCN are congruent
 - AB=BC  (sides of square)
 - BM=CN (half sides of square)
 - angle B = angle C (adjacent sides of square are perpendicular)
 => triangles ABM and BCN are congruent (SAS)

Step: find angle AQB
 - angle AQB = QMB+MBQ   (exterior angles of a triangle)
                      = BNC+MBN   (corresponding angles of congruent triangles)
                      = 90 degrees   (exterior angle of triangle BNC)

The answer is a because i went through all the other ones that it didn’t come out right