A face of a solid is any one of the flat surfaces of a prism or a pyramid. a pattern of two-dimensional shapes that can be folded to form a solid figure. a solid figure with a base that is a polygon and sides that are triangles that meet at the top. the total area of the surface of a solid figure.

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.