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Grade 11Trigonometry

please please answer this question if tan alpha =√a where a is rational number which is not a perfect square then which of the following is rational number
a.sin2 alpha
b.tan2 alpha
c.cos2 alpha
d.cot alpha

Profile image of SanchiSSonawane
7 Years agoGrade 11
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2 Answers

Profile image of Arun
ApprovedApproved Tutor Answer7 Years ago
cos 2 alpha = 1 – tan^2 alpha / 1 + tan^2 alpha
 
 = 1 – a / 1+a
 
Hence a rational number
 
So option 3 is correct
Profile image of yathartha gupta
ApprovedApproved Tutor Answer7 Years ago
Cot alp

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