A:2—甲基—2—丁烯
B:3—甲基—1—丁烯
C:2,3—二甲基—1—丁烯
D:3—甲基—1—丁炔
Experts said it was that Malaysia Airlines Flight 370(马航370) had changed course and turned back toward Kuala Lumpur(吉隆坡).
将矩形纸片ABCD按如图所示的方式折叠.恰好得到菱形AECF.若AD=3,则菱形AECF的面积为( )