如图,△ABC中,AB=AC,∠A=36°,求证BC/AB=√5-1/2

还有一个条件：BD平分∠ABC,对吗?
证明：∵∠A=36°,AB+C,
∴∠ABC=∠C=72°,
∵BD平分∠ABC,
∴∠DBC=∠ABD=36°=∠A,
∠BDC=72°=∠C,
∴AD=BD=BC,
又∠DBC=∠A,∠C=∠C,
∴ΔCBD∽ΔCBA,
∴BC/CD=AC/BC,
BC/(AB-BC)=AB/BC,
BC^2=AB^2-AB*BC,
(BC/AB)^2+(BC/AB)-1=0,
设BC/A=X(X>0).
∴X^2+X-1=0,
X=(-1+√5)/2(取正),
∴BC/AB=(√5-1)/2.