Now, since a perpendicular from D to AB bisects AB, D lies on perpendicular bisector of AB. Hence, it is equidistant from A and B.
→ DA = DB. But, DB is a diagonal of Rhombus.
Further, since this is a Rhombus, DA = AB (all sides are equal in Rhombus)
→ DA = DB = AB
→ Triangle DAB is equilateral triangle
→ Angle A = 60 degress.
Therefore angles of Rhombus are:
A = C = 60 degrees ; B = D = 120 degrees