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If `tan1^(@).tan2^(@).tan^(@)"………tan89^(@) = 4x^(2) + 2x` then the value of `x` isA. `sin"(pi)/(5)`B. `cos"(pi)/(5)`C. `sin"(pi)/(10)`D. `cos"(4pi)/(5)` |
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Answer» Correct Answer - C::D `tan1^(0).tan2^(0).tan3^(0)"……"tan89^(0) = 4x^(2) + 2x = 1` `rArr 4x^(2) + 3=2x - 1 = 0 rArr x(-1 +-sqrt(5))/(4)` `rArr (sqrt(5) - 1)/(4) = sin (pi)/(10)` or `-((sqrt(5) + 1)/(4)) = cos(4pi)/(5)` |
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