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In a ` A B C`if `b+c=3a ,t h e ncotB/2dotcotC/2`has the value equalto:``4b. 3 c. 2d. 1A. `4`B. `3`C. `2`D. `1` |
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Answer» Correct Answer - C In `a Delta ABC if b + c = 3a` ………… `cot.(B)/(2).cot.(C )/(2)=(s(s-b))/(Delta)(s(s-c))/(Delta)((s-a))/(s-a) = (s)/(s-a)` `= (2s)/(2s-2a)` but `a+b+c = 4a implies 2s = 4a` Hence `cot. (B)/(2). cot. (C )/(2)` `= (4a)/(2a) = 2I` |
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