已知 $\stackrel{\rightharpoonup }{e_1},\stackrel{\rightharpoonup }{e_2}$是空间单位向量， $\stackrel{\rightharpoonup }{e_1}·\stackrel{\rightharpoonup }{e_2}=\frac{1}{2}$，若空间向量 $\stackrel{\rightharpoonup }{b}$满足 $\stackrel{\rightharpoonup }{b}·\stackrel{\rightharpoonup }{e_1}=2,\stackrel{\rightharpoonup }{b}·\stackrel{\rightharpoonup }{e_2}=\frac{5}{2}$，且对于任意 $x,y\in R$， $\left|\stackrel{\rightharpoonup }{b}-(x\stackrel{\rightharpoonup }{e_1}+y\stackrel{\rightharpoonup }{e_2})\right|\ge \left|\stackrel{\rightharpoonup }{b}-(x_0\stackrel{\rightharpoonup }{e_1}+y_0\stackrel{\rightharpoonup }{e_2}\right|=1,(x_0,y_0\in R)$，则 $x_0=$， $y_0=$， $\left|\stackrel{\rightharpoonup }{b}\right|=$．