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In `Delta ABC` if `AB = x, BC = x + 1, angleC = (pi)/(3)`, then the less integer value of x isA. 6B. 7C. 8D. none of these |
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Answer» Correct Answer - B Using cosine rule, we get `x^(2) = (x + 1)^(2) + b^(2) -2 (x + 1) b cos.(pi)/(3)` `rArr 0 = 2x + 1 + b^(2) - (x +1) b` `rArr b^(2) -(x +1) b + 2x + 1 = 0` Since b is real, we have `rArr (x + 1)^(2) - 4 (2x +1) ge 0` `rarr x^(2) -6x - 3 ge 0` `rArr x ge 3 + sqrt12` The least integral value of x is 7 |
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