If x and y are acute angle such that x+y=90degree, which of the following must be true?
1. sinx=cosy
2. sin(90degree - x) = cos(90degree - y)
3. tan x tan y=1
Ans: All of them must be true
May anyone pls explain to me how to work out this question, thanks very much!!!
F.4 maths URGENT!!
2008-04-28 3:39 am
回答 (2)
2008-04-28 4:36 am
✔ 最佳答案
(1)since x+y=90osin(90o-x)=siny=cosx
so,sinx=cosy
notice:sin(90o-x)=cosx
(2)sin(90o-x)=cosy
cos(90o-y)=sinx
from(a),sinx=cosy
so,sin(90o-x)=cos(90o-y)
(3)tanxtany
=tan(90o-y)tany
=tany/tany
=1
notice:tan(90o-y)=1/tany
All the statements are true.
唔明歡迎再問
2008-04-28 3:51 am
X+Y=90
X=90-Y
Then, sinX=sin(90-Y)
=cosY
cos(90-Y)=sinY
=sin(90-X)
tanXtanY=tan(90-Y)tanY
=(1/tanY)tanY
=1
X=90-Y
Then, sinX=sin(90-Y)
=cosY
cos(90-Y)=sinY
=sin(90-X)
tanXtanY=tan(90-Y)tanY
=(1/tanY)tanY
=1
收錄日期: 2021-04-13 15:29:20
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