The graphs of the two equations y = ax + bx + c and y= A x² + B x + C, such that a and A have different
signs and that the quantities b2 - 4 ac and BP-4 AC
are both negative,​

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.