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Question : 27 of 160
Marks:
+1,
-0
Solution:
The given relation is
a2+2bc−(b2+c2)‌‌=ab‌sin‌‌cos‌ a2+2bc−(b2+c2)‌‌=‌ab‌sin‌C a2−(b2+c2−2bc)‌‌=‌ab‌sin‌C a2−(b−c)2‌‌=‌ab‌sin‌C (a−b+c)(a+b−c)‌‌=‌ab‌sin‌C 4(s−b)(s−c)‌‌=∆ 4‌‌=‌| √s(s−a)(s−b)(s−c) |
| (s−b)(s−c) |
4‌‌=√‌⇒cot‌=4 tan‌‌‌=‌ The expression for
tan‌A is
tan‌A=‌ =‌ =‌ Then
cot‌A=‌ cot(π−(B+C))=‌ This implies
cot(B+C)=−‌
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