text: 7.3 餘弦公式
  
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  7.3 餘弦公式 - PowerPoint PPT Presentation
  
  7.3 餘弦公式. 附加例題 3 附加例題 4. 圖中所示， ABCD 為一四邊形，已知 AD = 及 AC = ，求 DC 。. 7.3 附加例題 3. 解. = ( ) 2 + DC 2  2( )(DC) cos 60 . 捨去. DC 2  DC  6 = 0. ( DC  4)(DC + ) = 0. . 附加例題 3. 圖中所示， ABCD 為一四邊形，已知 AD = 及 AC = ，求 DC。. 解. 連接 AC。.
  
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  PowerPoint Slideshow about ' 7.3 餘弦公式' - ronald
  
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  7.3 餘弦公式
  
  = ( )2 + DC22( )(DC) cos 60
  
  DC2 DC  6 = 0
  
  (DC  4)(DC + ) = 0
  
  AC2 = AD2 + DC22 (AD)(DC) cos 60
  
  DC = 4
  
  7.3 附加例題 4
  
  x
  
  y
  
   4 = x2 + y2 xy ………………… (1)
  
   16 = x2 + y2 + xy ………………… (2)
  
  12 = 2 xy
  
  xy = 3
  
  AB2 = AE2 + BE2 2(AE)(BE) cosAEB
  
  42 = x2 + y2 2xy cos (180 45)
  
  (2)  (1)，
  
  = 4 ( xy sin 45)
  
  = 2 (3 )( )
  
  ABCD 的面積 = 4 AEB 的面積
  
  = 6
explanation: The document is a PowerPoint presentation slide about the cosine formula (餘弦公式) in mathematics. It contains two additional examples (附加例題 3 and 附加例題 4) that involve solving for unknown lengths and areas using the cosine formula. Each example includes a problem statement and a detailed solution.
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distilabel_metadata.content: 7.3 餘弦公式
  
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  7.3 餘弦公式 - PowerPoint PPT Presentation
  
  7.3 餘弦公式. 附加例題 3 附加例題 4. 圖中所示， ABCD 為一四邊形，已知 AD = 及 AC = ，求 DC 。. 7.3 附加例題 3. 解. = ( ) 2 + DC 2  2( )(DC) cos 60 . 捨去. DC 2  DC  6 = 0. ( DC  4)(DC + ) = 0. . 附加例題 3. 圖中所示， ABCD 為一四邊形，已知 AD = 及 AC = ，求 DC。. 解. 連接 AC。.
  
  I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
  
  PowerPoint Slideshow about ' 7.3 餘弦公式' - ronald
  
  An Image/Link below is provided (as is) to download presentation
  
  Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.
  
  - - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
  Presentation Transcript
  
  7.3 餘弦公式
  
  = ( )2 + DC22( )(DC) cos 60
  
  DC2 DC  6 = 0
  
  (DC  4)(DC + ) = 0
  
  AC2 = AD2 + DC22 (AD)(DC) cos 60
  
  DC = 4
  
  7.3 附加例題 4
  
  x
  
  y
  
   4 = x2 + y2 xy ………………… (1)
  
   16 = x2 + y2 + xy ………………… (2)
  
  12 = 2 xy
  
  xy = 3
  
  AB2 = AE2 + BE2 2(AE)(BE) cosAEB
  
  42 = x2 + y2 2xy cos (180 45)
  
  (2)  (1)，
  
  = 4 ( xy sin 45)
  
  = 2 (3 )( )
  
  ABCD 的面積 = 4 AEB 的面積
  
  = 6
distilabel_metadata.role: user
distilabel_metadata.raw_output_q_a_detector_0: The document is a PowerPoint presentation slide about the cosine formula (餘弦公式) in mathematics. It contains two additional examples (附加例題 3 and 附加例題 4) that involve solving for unknown lengths and areas using the cosine formula. Each example includes a problem statement and a detailed solution.
  
  Label: question-and-answer