(3) study the insolation curves in relation to the annual curve of the subsolar point. compare times of maximum and minimum values at 60°n and 40°s. explain how these two curves differ in timing based on the annual curve of the subsolar point.

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.