10th Class Mathematics Introduction to Trigonometry Question Bank MCQs - Introduction to Trigonometry

  • question_answer
    If \[\tan \theta =\frac{a}{b},\]then \[\frac{(a\sin \theta -b\cos \theta )}{(a\sin \theta +b\cos \theta )}=\]

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

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

    C) \[\frac{{{a}^{2}}}{({{a}^{2}}+{{b}^{2}})}\]

    D) \[\frac{{{b}^{2}}}{({{a}^{2}}+{{b}^{2}})}\]

    Correct Answer: B

    Solution :

    [b] We have \[\tan \theta =\frac{a}{b}\]
    Now,\[\frac{(a\sin \theta -b\cos \theta )}{(a\sin \theta +b\cos \theta )}=\frac{(a\tan \theta -b)}{(a\tan \theta +b)}\]
    (Dividing numerator and denominator by \[\cos \theta \]]
    \[=\frac{\left( a\times \frac{a}{b}-b \right)}{\left( a\times \frac{a}{b}+b \right)}=\frac{({{a}^{2}}-{{b}^{2}})}{({{a}^{2}}+{{b}^{2}})}\]


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