InterviewSolution
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InterviewSolution
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Which of the following numbers is rational?A. sin `15^(@)`B. `cos 15^(@)`C. sin `15^(@)` cos `15^(@)`D. sin `15^(@)` cos `75^(@)` |
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Answer» Correct Answer - C Since, `sin 15^(@) = (1)/(2) sqrt(2-sqrt(3)) and cos 15^(@) = (1)/(2) sqrt(2+sqrt(3))` and `sin 15^(@) cos 75^(@) = sin 15^(@).sin 15^(@) = (1)/(4)(2 - sqrt(3))` Therefore, all these values are irrational and `sin 15^(@) cos 15^(@) = (1)/(2).2 sin 15^(@) cos 15^(@)` `=(1)/(2).sin 30^(@) = (1)/(4)`, which is rational. |
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