It is known that in a parallelogram ABCD, points E and F are on edges AB and BC respectively. (1) if AB = 10, the distance between AB and CD is 8, AE = EB, BF = FC, the area of △ DEF is calculated. (2) if the areas of △ ade, △ bef and △ CDF are 5, 3 and 4, the area of △ DEF is calculated

It is known that in a parallelogram ABCD, points E and F are on edges AB and BC respectively. (1) if AB = 10, the distance between AB and CD is 8, AE = EB, BF = FC, the area of △ DEF is calculated. (2) if the areas of △ ade, △ bef and △ CDF are 5, 3 and 4, the area of △ DEF is calculated

(1) (2) let AB = x, ab = be, be, be, be, be, BF = CF, and \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\inthis paper, we present a method for the determination of trace elements, AE = x-6xxy The results are as follows: (XY) 2-24 & nbsp; XY + 80 = 0, xy = 20 or 4, ∵ sabcd = XY ＞ s △ AED = 5, ∵ xy = 4 incompatible, ∵ xy = 20, s △ def = sabcd-s △ aed-s △ bef-s △ DCF = 20-5-3-4 = 8