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標題:
maths
發問:
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!
最佳解答:
其他解答:
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)
maths
發問:
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!
最佳解答:
此文章來自奇摩知識+如有不便請留言告知
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.其他解答:
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)
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