JEE Main & Advanced Mathematics Triangles & Properties of Triangle Question Bank Self Evaluation Test - Properties of Triangles and Height & Dstances

  • question_answer
    In a \[\Delta ABC,\]\[\frac{\sin A}{\sin C}=\frac{\sin (A-B)}{\sin (B-C)},\] then \[{{a}^{2}},{{b}^{2}},{{c}^{2}}\] are such that

    A) \[{{b}^{2}}=ac\]

    B) \[{{b}^{2}}=\frac{{{a}^{2}}{{c}^{2}}}{{{a}^{2}}+{{c}^{2}}}\]

    C) They are in A.P.

    D) \[{{b}^{2}}={{a}^{2}}+{{c}^{2}}\]

    Correct Answer: C

    Solution :

    [c] \[\frac{\sin A}{\sin C}=\frac{\sin (A-B)}{\sin (B-C)}\Rightarrow \frac{\sin (B+C)}{\sin (A+B)}=\frac{\sin (A-B)}{\sin (B-C)}\] \[\Rightarrow {{\sin }^{2}}B-{{\sin }^{2}}C={{\sin }^{2}}A-{{\sin }^{2}}B\] \[\Rightarrow {{\sin }^{2}}A,{{\sin }^{2}}B,{{\sin }^{2}}C\] and hence \[{{a}^{2}},{{b}^{2}},{{c}^{2}}\] are in A.P.


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