AB || CD and AC is oblique ;
So : Angle ( BAC ) = Angle ( DCA )
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∆ ABC - ∆ ACD :
(1) AB = CD
(2) Angle ( BAC ) = Angle ( DCA )
(3) AC = AC
So According to (1) , (2) , (3) :
∆ ABC =~ ∆ ACD
Well, if two triangles are deposited, all their components are equal peer to peer.
So : AD = BC
