(2): I can't see clearly, sorry, I can't help you.
(3): Because DE is parallel to AB, the included angles of CDE and CAB, CED and CBA are equal respectively, satisfying the conditions of triangle similarity, so △CDE∽△CAB.
(3) Because the two triangles are similar and DE: AB = 1: 2, according to the similar triangles area ratio, the ratio of △CDE area to △ cab area is 1: 4.
Maybe you haven't learned the similarities yet. Don't worry, don't worry about the super-class problem.
Kneel down and hope the questioner will make a quick decision. Baidu urgently needs to know the main points. Thank you.