7.3 餘弦公式

1 / 6

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