涛涛GWD2-30？

yaoyao99

Please list the question number in the title (e.g. GWD-2-31).

Someone asked this a few days ago.  BCE = (BED - BCD) / 2

yaoyao99

BCE = (BED - BCD) / 2

yaoyao99

BE = ED, BC = CD, CE = CE => BCE = ECD
BCE = BED - BCD - ECD => BCE = BED - BCD - BCE => 2BCE = BED - BCD => BCE = (BED - BCD) / 2
You can get the area of BCD because BCD = ABCD/2
You can also get the area of BCD = BD * (CE + CA * 0.5) / 2

yaoyao99

Umum, the graph in GWD is very misleading.  Try drawing it out on paper and then you'll realize everything is on the same plane.