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\operatorname{cosec} 18^{\circ} is a root of the equation :
Option: 1 x^{2}+2 x-4=0
Option: 2 4 x^{2}+2 x-1=0
Option: 3 x^{2}-2 x-4=0
Option: 4 x^{2}-2 x+4=0

Answers (1)

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\operatorname{cosec} 18^{\circ}= \frac{1}{\sin 18^{\circ}}= \frac{4}{\sqrt{5}-1}= \sqrt{5}+1= \alpha
Let\, \beta = 1-\sqrt{5}
\alpha +\beta = 2 ;\alpha \, \beta = -4
\Rightarrow x^{2}-2x-4= 0
option (3)

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Kuldeep Maurya

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