9.(2023春•霞山区校级月考)已知α∈(0,2π)\alpha \in (0,2\pi )α∈(0,2π),且5sinα=8sinα25\sin \alpha =8\sin \frac{\alpha }{2}5sinα=8sin2α,则tanα2=(\tan \frac{\alpha }{2}=(tan2α=( )))