Solve the following equations for 0°∠x∠360°.(Correct your answers to 1 decimal place if neceaasry.)唔該d步驟詳細d呀~thx~
1.tanx-3siinx=0
2.sin²θ+3cos²θ=2+cosθ
MATH(Trigonometry)
2007-05-11 2:19 am
回答 (2)
2007-05-11 2:29 am
✔ 最佳答案
1.tanx-3sinx=0
sinx-3sinxcosx=0
sinx(1-3cosx)=0
sinx=0orcosx=1/3
x=0,180,360or70.5,289.5
2.
sin²θ+3cos²θ=2+cosθ
1+2cos²θ=2+cosθ
2cos²θ-cosθ-1=0
(2cosθ+1)(cosθ-1)=0
cosθ=-0.5or1
θ=120,240or0,360
2007-05-10 18:34:22 補充：
to:myisland8132(2cosθ-1)(cosθ+1)=2cos²θ+2cosθ-cosθ-1=2cosθ+cosθ-1(=/=2cosθ-cosθ-1)
參考: me
2007-05-11 2:41 am
1)
tanx - 3sinx = 0
sinx - 3sinxcosx = 0
sinx(1 - 3cosx) = 0
2)
sin^2@ + 3cos^2@ = 2 + cos@
1 + 2cos^2@ = 2 + cos@
2cos^2@ - cos@ - 1 = 0
tanx - 3sinx = 0
sinx - 3sinxcosx = 0
sinx(1 - 3cosx) = 0
2)
sin^2@ + 3cos^2@ = 2 + cos@
1 + 2cos^2@ = 2 + cos@
2cos^2@ - cos@ - 1 = 0
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