在直三棱柱ABC-A1B1C1中,角BAC等于九十度,M,N分别是A1B和B1C1的中点,求证MN平行片面A1ACC1

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• 在直三棱柱ABC-A1B1C1中,角BAC等于九十度,M,N分别是A1B和B1C1的中点,求证MN平行片面A1ACC1
• 如图，在直三棱柱ABC-A1B1C1中，AC⊥BC，AC=BC=CC1，M、N分别是A1B、B1C1的中点．（Ⅰ）求证：MN⊥平面A1BC；（Ⅱ）求直线BC1和平面A1BC所成角的大小．
• 在直三棱柱ABC-A1B1C1中,角BAC等于九十度,M,N分别是A1B和B1C1的中点,求证MN平行片面A1ACC1
• 如图，在直三棱柱ABC-A1B1C1中，AC⊥BC，AC=BC=CC1，M、N分别是A1B、B1C1的中点． （Ⅰ）求证：MN⊥平面A1BC； （Ⅱ）求直线BC1和平面A1BC所成角的大小．
• 如图，在直三棱柱ABC-A1B1C1中，AC⊥BC，AC=BC=CC1，M、N分别是A1B、B1C1的中点．（Ⅰ）求证：MN⊥平面A1BC；（Ⅱ）求直线BC1和平面A1BC所成角的大小．
• 直三棱柱ABC-A1B1C1,角BAC=90度,AB=AC=根号2,AA1=1,点M,N分别为A1B和B1C1的中点.证明MN平行于平面A1ACC1
• 如图，在直三棱柱ABC-A1B1C1中，AC⊥BC，AC=BC=CC1，M、N分别是A1B、B1C1的中点． （Ⅰ）求证：MN⊥平面A1BC； （Ⅱ）求直线BC1和平面A1BC所成角的大小．
• 直三棱柱ABC-A1B1C1,角BAC=90度,AB=AC=根号2,AA1=1,点M,N分别为A1B和B1C1的中点.证明MN平行于平面A1ACC1
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