A skier starts from rest at the top of a 20°~incline and skis in a straight line to the bottom of the slope, a distance d (measured along the slope) of 400 m. If the coefficient of kinetic friction between the skis and the snow is 0.2, calculate the skier\textquotesingle s speed at the bottom of the run.                   
Overseas Competition->Knowledge Point->Combinatorics->Patterns of Figures->Change of Position (Slides)