根据已知,b/a=c=b.即b^2=ac,,由勾股定理a^2+b^2=c^2,,联立1,2得ac=c^2-a^2,两边同除c^2,得(a/c)^2+(a/c)=1,解得a/c=(-1+根号下5)/2.应该很清楚了!