ABCD is a quadrilateral in which AD = BC. E, F, G and H are mid-points of AB, BD, CD and AC respectively. Then EFGH is a -
Rhombus
Using mid-point theorem,
In ΔDBC,GF=12BC
In ΔACD,GH=12AD
In ΔABC,EH=12BC
In ΔBAD,EF=12AD
Since AD = BC,
we can say that GF = GH = EH = EF
⇒ EFGH is a rhombus.