F.4 Amaths兩條

2007-12-02 5:15 am

回答 (2)

2007-12-02 5:39 am
✔ 最佳答案
As follows:

圖片參考:http://i190.photobucket.com/albums/z177/ansonluizzzz/1-5.jpg

( 1 ) sin^2@ / ( 1 + 2 cos^2 @ ) = 3 / 19
( 1 - cos^2 @ ) / ( 1 + 2 cos^2 @ ) = 3 / 19
25cos^2 @ = 16
cos^2 @ = 16 / 25
cos @ = - 4 / 5 since 180* < @ < 270*
tan @ = 3 / 4 and sec @ = - 5 / 4
So,
tan @ / ( 1 + sec @ )
= ( 3 / 4 ) / ( 1 - 5 / 4 )
= -3
2) sec @ ( sec @ - tan @ ) = x
sec^2 @ - sin@ sec^2 @ = x
sec^2 @ ( 1 - sin @ ) = x
( 1 - sin @ ) / ( 1 - sin^2 @ ) = x
1 / ( 1 + sin @ ) = x
sin @ = ( 1 - x ) / x or ( x - 1 ) / x
參考: My Maths Knowledge
2007-12-11 5:24 am
Ans:
1) - 3


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