假设边长为a,AE=x,
BE=AB-AE=a-x,
∠B=60==>∠BPE=30==>BP=2BE=2(a-x),
PC=BC-BP=a-2(a-x)=2x-a,
∠C=60==>∠CPD=30==>CD=PC/2=(2x-a)/2=x- a/2,
AD=AC-CD=a-(x- a/2)=3a/2 -x;
△AED的周长
=AE+AD+ED
=x+3a/2 -x+ED=3a/2+ED,
四边形EBCD的周长
=BE+ED+DC+CB
=(a-x)+ED+(x- a/2)+a
=3a/2+ED
得证.