如图,在三棱锥P-ABC中,AB垂直于BC,AB=BC=kPA,点O、D分别是AC、PC的中点,OP垂直于底面ABC(1)当k=0.5时,求直线PA与平面PBC所成角的正弦值(2)当k为何值时,O在平面PBC内的射影恰好为三角形ABC的重心
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![如图,在三棱锥P-ABC中,AB垂直于BC,AB=BC=kPA,点O、D分别是AC、PC的中点,OP垂直于底面ABC(1)当k=0.5时,求直线PA与平面PBC所成角的正弦值(2)当k为何值时,O在平面PBC内的射影恰好为三角形ABC的重心](/uploads/image/z/5335701-69-1.jpg?t=%E5%A6%82%E5%9B%BE%2C%E5%9C%A8%E4%B8%89%E6%A3%B1%E9%94%A5P-ABC%E4%B8%AD%2CAB%E5%9E%82%E7%9B%B4%E4%BA%8EBC%2CAB%3DBC%3DkPA%2C%E7%82%B9O%E3%80%81D%E5%88%86%E5%88%AB%E6%98%AFAC%E3%80%81PC%E7%9A%84%E4%B8%AD%E7%82%B9%2COP%E5%9E%82%E7%9B%B4%E4%BA%8E%E5%BA%95%E9%9D%A2ABC%EF%BC%881%29%E5%BD%93k%3D0.5%E6%97%B6%2C%E6%B1%82%E7%9B%B4%E7%BA%BFPA%E4%B8%8E%E5%B9%B3%E9%9D%A2PBC%E6%89%80%E6%88%90%E8%A7%92%E7%9A%84%E6%AD%A3%E5%BC%A6%E5%80%BC%EF%BC%882%EF%BC%89%E5%BD%93k%E4%B8%BA%E4%BD%95%E5%80%BC%E6%97%B6%2CO%E5%9C%A8%E5%B9%B3%E9%9D%A2PBC%E5%86%85%E7%9A%84%E5%B0%84%E5%BD%B1%E6%81%B0%E5%A5%BD%E4%B8%BA%E4%B8%89%E8%A7%92%E5%BD%A2ABC%E7%9A%84%E9%87%8D%E5%BF%83)
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