28．（2023春•石景山区期末）已知角α\alphaα的顶点与坐标原点OOO重合，始边与xxx轴的非负半轴重合，终边过点P(−55,255)P({-\frac{\sqrt{5}}{5},\frac{2\sqrt{5}}{5}})P(−55,525)．（Ⅰ）求sinα\sin \alphasinα，cos(π−α)\cos (\pi -\alpha )cos(π−α)；（Ⅱ）若角β\betaβ满足tan(α−β)=13\tan ({\alpha -\beta })=\frac{1}{3}tan(α−β)=31，求tan(2α−β)\tan (2\alpha -\beta )tan(2α−β)的值．