Cho hình chóp S.ABC có đáy ABC là tam giác đều cạnh a, cạnh SA vuông góc với mặt đáy và . Gọi M là trung điểm của SC. Tính côsin của góc giữa đường thẳng BM và mặt phẳng .

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Một số câu hỏi khác có thể bạn quan tâm.

• Choose the best answer for the following sentence:

  I think ______________a lie to our parents is unacceptable.

   

• Choose the best answer for the following sentence:

  A true friend will never _______________ whenever you are in difficulty and need his help.

   

• Choose the best answer for the following sentence:

  Friendship brings us ____________ best of all in life.

   

• Choose the best answer for the following sentence:

  Our company is ______________ contract to supply enough materials for them to produce.

   

• Choose the best answer for the following sentence:

  The volunteers are keen __________ coming to that remote area.

   

• Find a mistake in the four underlined parts of the sentence and correct it:

  It was them that killed the bank manager.

• Choose the best answer for the following sentence:

  Most parents have total confidence ___________  the school.

   

• Choose the best answer for the following sentence:

   Friends make us ___________ more comfortable and cheerful in life.

   

• Choose the best answer for the following sentence:

  ''If you are late again, I will sack you,'' the boss ___________ him.

   

• Choose the best answer for the following sentence:

  John said that at 9 o’clock the day before he ____________ the monthly report.