Cho hình bình hành ABCD, O là giao điểm của hai đường chéo AC và BD. Có các khẳng định sau:
(a) Vectơ $\overrightarrow{\mathrm{OA}} - \overrightarrow{\mathrm{OB}}$ là vectơ đối của vectơ $\overrightarrow{\mathrm{OA}} + \overrightarrow{\mathrm{OB}}$
(b) Vectơ $\overrightarrow{\mathrm{OA}} - \overrightarrow{\mathrm{OB}}$ là vectơ đối của vectơ $\overrightarrow{\mathrm{AO}} - \overrightarrow{\mathrm{BO}}$
(c) Vectơ $\overrightarrow{\mathrm{DA}} + \overrightarrow{\mathrm{AB}}$ là vectơ đối của vectơ $\overrightarrow{\mathrm{BC}} + \overrightarrow{\mathrm{CD}}$
(d) Vectơ $\overrightarrow{\mathrm{DA}} + \overrightarrow{\mathrm{AB}}$ là vectơ đối của vectơ $\overrightarrow{\mathrm{CB}} - \overrightarrow{\mathrm{DC}}$
Trong các khẳng định trên khẳng định đúng là

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Một số câu hỏi khác có thể bạn quan tâm.

• Choose the correct sentence which is built from the words and phrases given:

  man / sentence 15 years / prison / he / prove / guilty.
  
  

• Choose the correct sentence which is built from the words and phrases given:

  school-leavers / choose / college / employment / immediate.
  
  

• Choose one sentence that has the same meaning to the root one:

  David drove so fast, it was very dangerous.
  
  

• Choose one sentence that has the same meaning to the root one:

  The captain to his men, "Abandon the ship immediately!"
  
  

• Choose one sentence that has the same meaning to the root one:

  The critics undervalued his new book.
  
  

• Choose one sentence that has the same meaning to the root one:

  "Shall I make you a coffee?" the girl said to the lady.
  
  

• Choose one sentence that has the same meaning to the root one:

  No sooner had she put the telephone down than her boss rang back.
  
  

• Choose the best answer for the following sentence:

  “Do you think Mary will take the job you offered her?”

  ''I don’t know. She seemed ___________ in it, however.''
   

• Choose the best answer for the following sentence:

  “The students all went to the circus yesterday.” “I heard it was really ____________.''

   

• Choose the best answer for the following sentence:

  “I was ____________ that Jane couldn’t come to the party.” “Her boss made her work overtime.”