4. （2021秋•安庆期末）已知sin(15∘+α)=23\sin ({{{15}\circ }+\alpha })=\frac{\sqrt{2}}{3}sin(15∘+α)=32，则sin(240∘−2α)=(\sin (240\circ -2\alpha )=(sin(240∘−2α)=( )))