OP=PQ
P点的坐标(b/2,y)
b/2* y=k
y=2k/ b
P点的坐标(b/2,2k/ b)
(2)若△POQ的面积为1
S△POQ
=1/2*OQ*YP
=1/2*b*2k/ b
=k
k=1
双曲线的解析式y=1/x