10th Class Mathematics Introduction to Trigonometry Question Bank Trigonometry

  • question_answer
      If \[\tan \theta =\frac{a}{b}\], find the value of \[\frac{\text{a}\,\sin \theta -b\cos \theta }{\text{a}\sin \theta +b\,cos\theta }\]

    A)  \[\frac{{{\text{a}}^{\text{2}}}\text{-}{{\text{b}}^{\text{2}}}}{{{\text{a}}^{\text{2}}}\text{+}{{\text{b}}^{\text{2}}}}\]

    B)  \[\frac{{{b}^{\text{2}}}\text{-}{{\text{a}}^{\text{2}}}}{{{b}^{\text{2}}}\text{+}{{\text{a}}^{\text{2}}}}\]

    C)  \[\frac{{{a}^{\text{2}}}\text{+}{{\text{b}}^{\text{2}}}}{{{a}^{\text{2}}}\text{-}\,{{\text{b}}^{\text{2}}}}\]                       

    D)  None of these

    Correct Answer: A

    Solution :

    (a): \[\frac{a\frac{\sin \theta }{\cos \theta }-b\frac{\cos \theta }{\cos \theta }}{a\frac{\sin \theta }{\cos \theta }+b\frac{\cos \theta }{\cos \theta }}=\frac{a\times \frac{a}{b}-b}{a\times \frac{a}{b}+b}\] \[=\frac{{{a}^{2}}-{{b}^{2}}}{{{a}^{2}}+{{b}^{2}}}\]              


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