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Question
In the following questions, two statements (i) and (ii) are given. Choose the valid statement.
(i) If θ = 15° then `(sin 3θ)/(cos 4θ) = sqrt(2)`
(ii) cot 20° cot 40° cot 50° cot 70° = 2
Options
Only (i)
Only (ii)
Both (i) and (ii)
Neither (i) nor (ii)
MCQ
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Solution
Only (i)
Explanation:
(i) With θ = 15°.
`(sin 3θ)/(cos 4θ)`
= `(sin 45^circ)/(cos 60^circ)`
= `(sqrt(2)/2)/(1/2)`
= `sqrt(2)`
(ii) cot 20° · cot 40° · cot 50° · cot 70°
= cot 20° · cot 40° · tan 40° · tan 20°
= 1 (not 2)
So, (ii) is false.
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