解答:解:(1)作BD⊥x轴于D,如图,在Rt△OBD中,tan∠BOC= BD OD = 1 2 ,∴ ?n m = 1 2 ,即m=-2n,把点B(m,n)代入y1=-x+2得n=-m+2,∴n=2n+2,解得n=-2,∴m=4,∴B点坐标为(4,-2),把B(4,-2)代入y2= k x 得k=4×(-2)=-8,∴反比例函数解析式为y2=- 8 x ;(2)当0<x<4时,y2的取值范围是y2<-2,当x<0时,y2>0.