1.If cosθ=9∕41,find sinθ and tanθ
2.x(x+a)－10≡(x－b)(x+c) set the valus of a、b andc
Please help，thx!
maths
2008-07-23 7:22 am
回答 (2)
2008-07-23 7:33 am
✔ 最佳答案
cosθ=9∕41/cos^2 θ=81/1681
1-sin^2 θ=81/1681
sin^2 θ=1600/1681
sinθ=40/41//
tan θ= sinθ/cosθ=(40/41)/(9/41)=40/9//
2008-07-22 23:36:24 補充：
x(x+a)－10≡(x－b)(x+c)
x^2 +ax - 10= x^2 +(c-b)x-bc= 0
a=c-b--(1)
bc=10--(2)
there are only 2 equations ,but there are 3 unknown number ,
so we can't find the ans.
2008-07-23 3:57 pm
1.
cosθ=9∕41
sinθ=40/41
tanθ=40/9
2.
L.H.S.=x(x+a)
=x2+ax-10
R.H.S.=(x－b)(x+c)
=x2-bx+cx-bc
=x^2+(c-b)x-bc
Comparing L.H.S and R.H.S. the like term,
a=c-b______________(1)
10=bc______________(2)
cosθ=9∕41
sinθ=40/41
tanθ=40/9
2.
L.H.S.=x(x+a)
=x2+ax-10
R.H.S.=(x－b)(x+c)
=x2-bx+cx-bc
=x^2+(c-b)x-bc
Comparing L.H.S and R.H.S. the like term,
a=c-b______________(1)
10=bc______________(2)
收錄日期: 2021-04-23 20:35:03
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20080722000051KK03462