InterviewSolution
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InterviewSolution
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In `Delta ABC , If b/(c^2-a^2)+a/(c^2-b^2)=0` thenA. `(pi)/(2)`B. `(pi)/(4)`C. `(2pi)/(3)`D. `(pi)/(3)` |
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Answer» Correct Answer - D We have, `(a)/(sinA)=(b)/(sinB)=(c)/(sinC)=k("say")` `therefore (a)/(b^(2)-c^(2))+(c)/(b^(2)-a^(2))=0` `implies (k sinA)/(k^(2)(sin^(2)B-sin^(2)c))+(k sinC)/(k^(2)(sin^(2)B-sin^(2)A))=0` `implies (sinA)/(sin(B+C)sin(B-C))+(sinC)/(sin(B+A)sin(B-A))=0` `implies(sinA)/(sin(B+C)sin(B-C))+(sinC)/(sin(B+A)sin(B-A))=0` `implies(1)/(sin(B-C))+(1)/(sin(B-A))=0` `impliessin(B-A)+sin(B-C)=0` `impliessin(A-B)=sin(B-C)` `impliesA-B=B-CimpliesA+C=2BimpliesB=60^(@)` |
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