If 32tan8θ=2cos2α−3cosαand3cos3θ+6cos2θ−2cosθ−4=0, then general values of α is
A
nπ±2π3,nϵZ
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B
nπ+2π3,nϵZ
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C
2nπ±2π3,nϵZ
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D
2nπ+2π3,nϵZ
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Solution
The correct option is C2nπ±2π3,nϵZ 3cos3θ+6cos2θ−2cosθ−4=0⇒(3cos2θ−2)(cosθ+2)=0∴cos2θ=23⇒sec2θ=32∴tan2θ=12⇒tan8θ=116∴32tan8θ=2=2cos2α−3cosα ⇒cosα=−12orcosα=2(Notpossible)∴cosα=−12=cos2π3∴α=2nπ±2π3