[填空题]
A child slides down a slide ;q1kj ug,d jia dat,ot8hf857 with a 3bj* yonl)0mm.fb mn6 28$^{\circ}$ incline, and at the bottom her speed is precisely half what it would have been if the slide had been frictionless. Calculate the coefficient of kinetic friction between the slide and the child.
