①—You are Danny.
—Yes. I'm Danny.
②Look,I'm tall and fat. Who am I?
③Look at my eyes. My eyes are small and brown.
④My nose is big. My mouth is big,too.
____
已知函数f(x)=﹣3sinx+3cosx,若x1•x2>0,且f(x1)+f(x2)=0,则|x1+x2|的最小值为( )