选BOC=mOA+nOB即:OA·OC=m|OA|^2+nOA·OB即:|OC|cos(30°)=m即:m=√3|OC|/2OB·OC=mOA·OB+n|OB|^2即:√3|OC|cos(60°)=3n即:n=√3|OC|/6故:m/n=3