U=(15,6,7,8,9,10,11,12,13,14,15)
A=(5,6,7,8)
B=(5,7,911,13,15)
If C is subset of B, give an example of set C

Given: ae ≅ ce ; de ≅ be prove: abcd is a parallelogram. we have that ab || dc. by a similar argument used to prove that △aeb ≅ △ced, we can show that △ ≅ △ceb by. so, ∠cad ≅ ∠ by cpctc. therefore, ad || bc by the converse of the theorem. since both pair of opposite sides are parallel, quadrilateral abcd is a parallelogram.