12,13,15,16,19,19,19,20,21,25 find the mean

Which of those sequences is a geometric sequence

The volume of a cube is 8 in to the 3rd power. how long is each side?

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.