一到希望杯试题 As shown in the figure 25,i

来源：学生作业帮编辑：作业帮分类：数学作业时间：2024/07/04 17:58:29

一到希望杯试题
As shown in the figure 25,in△ABC we have AB=BC=CA,DF⊥AC,DE⊥AB.Please compare themagnitudes of the perimeter of △AEF and the perimeter of quadrilataral EBCF
中文大意：在正△ABC中 AB=BC=CA,BC上有一点D,DE⊥AB,DF⊥AC.试比较三角形AEF和四边形EBCF的周长

因为AB=BC=CA,且ED⊥AB,DF⊥AC,则∠EDB=∠FDC=30°,所以BD=2BE,DC=2FC,则四边形BCFE=EF+BE+FC+BD+DC=3BE+3FC+EF,
而C△AEF=AE+EF+AF=AB-BE+AC-FC+EF=2BC-BE-FC+EF=2(BD+DC)-BE-FC+EF=3BE+3FC+EF.
所以三角形AEF和四边形EBCF的周长相等

As in figure 2.In the circular As in figure，the area of square&nbs As in right figure，in a quadrilater 初中英语试题试题 The doctor thought The government &nbs 完形填空。 Known as the Animal Lady in t ...... , .,. -)