在三棱锥A-BCD中,侧面ABD、ACD是全等的直角三角形,AD是公共的斜边,且AD=根号3,BD=CD=1,另一个侧面是正三角形(1)求证:AD垂直BC(2)求二面角BACD的平面角的余弦值(3)在直线AC上是否存在一点E
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![在三棱锥A-BCD中,侧面ABD、ACD是全等的直角三角形,AD是公共的斜边,且AD=根号3,BD=CD=1,另一个侧面是正三角形(1)求证:AD垂直BC(2)求二面角BACD的平面角的余弦值(3)在直线AC上是否存在一点E](/uploads/image/z/5223670-70-0.jpg?t=%E5%9C%A8%E4%B8%89%E6%A3%B1%E9%94%A5A-BCD%E4%B8%AD%2C%E4%BE%A7%E9%9D%A2ABD%E3%80%81ACD%E6%98%AF%E5%85%A8%E7%AD%89%E7%9A%84%E7%9B%B4%E8%A7%92%E4%B8%89%E8%A7%92%E5%BD%A2%2CAD%E6%98%AF%E5%85%AC%E5%85%B1%E7%9A%84%E6%96%9C%E8%BE%B9%2C%E4%B8%94AD%3D%E6%A0%B9%E5%8F%B73%2CBD%3DCD%3D1%2C%E5%8F%A6%E4%B8%80%E4%B8%AA%E4%BE%A7%E9%9D%A2%E6%98%AF%E6%AD%A3%E4%B8%89%E8%A7%92%E5%BD%A2%EF%BC%881%EF%BC%89%E6%B1%82%E8%AF%81%EF%BC%9AAD%E5%9E%82%E7%9B%B4BC%EF%BC%882%EF%BC%89%E6%B1%82%E4%BA%8C%E9%9D%A2%E8%A7%92BACD%E7%9A%84%E5%B9%B3%E9%9D%A2%E8%A7%92%E7%9A%84%E4%BD%99%E5%BC%A6%E5%80%BC%EF%BC%883%EF%BC%89%E5%9C%A8%E7%9B%B4%E7%BA%BFAC%E4%B8%8A%E6%98%AF%E5%90%A6%E5%AD%98%E5%9C%A8%E4%B8%80%E7%82%B9E)
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