InterviewSolution
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यदि `A+B+C=pi`, तो सिद्ध कीजिए - `|(sin(A+B+C),sin(A+C),cosC),(-sinB,0,tanA),(cos(A+B),tan(B+C),0)|=0`. |
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Answer» यहाँ `A+B+C=pi` , तब `A+C=pi-B,A+B=pi-C,B+C=pi-A`. `therefore sin (A+B+C)=sin pi = 0`. `sin (A+C)=sin(pi-B)=sinB`, `cos (A+B)=cos (pi-C)=-cos C`, `tan (B+C)=tan(pi-A)=-tanA`. अब , L.H.S.`=|(sin(A+B+C),sin(A+C),cosC),(-sinB,0,tanA),(cos(A+B),tan(B+C),0)|` `=|(0,sin,cosC),(-sinB,0,tanA),(-cosC,tanA,0)|` `=sin B|(sinB,cosC),(-tanA,0)|-cosC|(sinB,cosC),(0,tanA)|`. (`C_1` के सापेक्ष प्रसार करने पर ) `=sinB(0+tanAcosC)-cosC(sinBtanA-0)` `=sinBtanA cos C-sinB tan A cos C` `=0=R.H.S`. |
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