In the space quadrilateral ABCD, e, F, G, h are the midpoint of AB, BC, CD, Da respectively. If AC ⊥ BD, efgh is what graph
∵ e, F, G and H are the midpoint, respectively
∴EF//AC,HG//AC,GF//BD,HE//BD
∴EF//HG,GF//HE
The efgh is a parallelogram
∵AC⊥BD
∴EF⊥BD
∴EF⊥GH
The quadrilateral efgh is a rectangle
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