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

  • question_answer
    If \[x=a\,\tan \theta \]and \[y=b\,\sec \theta ,\] then:

    A) \[\frac{{{y}^{2}}}{{{b}^{2}}}-\frac{{{x}^{2}}}{{{a}^{2}}}=1\]

    B) \[\frac{{{x}^{2}}}{{{a}^{2}}}+\frac{{{y}^{2}}}{{{b}^{2}}}=1\]

    C) \[\frac{{{x}^{2}}}{{{a}^{2}}}-\frac{{{y}^{2}}}{{{b}^{2}}}=1\]

    D) \[\frac{{{x}^{2}}}{{{a}^{2}}}-\frac{{{y}^{2}}}{{{b}^{2}}}=0\]

    Correct Answer: A

    Solution :

    [a] We have, \[x=a\tan \theta \] and \[y=b\sec \theta \]
    \[\Rightarrow \,\,\,\,\,\,\,\,\,\,\,\,\tan \theta =\frac{x}{a}\] and \[\sec \theta =\frac{y}{b}\]
    Putting these values in \[{{\sec }^{2}}\theta -{{\tan }^{2}}\theta =1,\] we get
    \[\frac{{{y}^{2}}}{{{b}^{2}}}-\frac{{{x}^{2}}}{{{a}^{2}}}=1\]


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