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

  • question_answer
    Match the following.
    Column - I Column - II
    P. \[1+\frac{{{\cot }^{2}}\theta }{1+\cos ec\theta }\] 1. \[2\tan \theta \]
    Q. \[\frac{\cos \theta }{\cos ec\theta +1}\] \[+\frac{\cos \theta }{\cos ec\theta -1}\] 2. \[{{\left( \frac{{{\sin }^{2}}\theta -{{\cos }^{2}}\theta }{\cos \theta \,\sin \theta } \right)}^{2}}\]
    R. \[{{\tan }^{2}}\theta +{{\cot }^{2}}\theta -2\] 3. \[{{\left( \cos ec\theta -\cot \theta  \right)}^{2}}\]
    S. \[\frac{1-\cos \theta }{1+\cos \theta }\] 4. \[\sec \theta \cot \theta \]

    A) P-3,      Q-4,      R-2,      S-1

    B) P-3,      Q-1,      R-4,      S-2

    C) P-2,      Q-3,      R-4,      S-1

    D) P-4,      Q-1,      R-2,      S-3

    Correct Answer: D

    Solution :

    \[P\to 4;\,Q\,\to 1;\,R\to 2;\,S\to 3\]
    (P) \[1+\frac{{{\cot }^{2}}\theta }{1+\cos ec\theta }\]
    \[=1+\frac{\cos e{{c}^{2}}\theta -1}{1+\cos ec\theta }\]
    \[=1+\frac{\left( \cos ec\theta  \right)\left( \cos ec\theta -1 \right)}{\left( \cos ec\theta +1 \right)}\]
    \[=1+\cos ec\theta -1\]
    \[=\cos ec\theta =\sec \theta \cot \,\theta \]
    (Q) \[\frac{\cos \theta }{\cos ec\theta +1}+\frac{\cos \theta }{\cos ec\theta -1}\]
    \[=\cos \theta \left( \frac{1}{\cos ec\theta +1}+\frac{1}{\cos ec\theta -1} \right)\]
    \[=\cos \theta \left( \frac{\cos ec\theta -1+\cos ec\theta +1}{\cos e{{c}^{2}}\theta -1} \right)\]
    \[=\frac{\cos \theta \left( 2\cos ec\theta  \right)}{{{\cot }^{2}}\theta }\]
    \[=2\frac{\cot \theta }{{{\cot }^{2}}\theta }\]
    \[=2\tan \theta \]
    (R) \[{{\tan }^{2}}\theta +{{\cot }^{2}}\theta -2={{\left( \tan \theta -\cot \theta  \right)}^{2}}\]
    \[={{\left( \frac{\sin \theta }{\cos \theta }-\frac{\cos \theta }{\sin \theta } \right)}^{2}}\]
    \[={{\left( \frac{{{\sin }^{2}}\theta -{{\cos }^{2}}\theta }{\cos \theta \sin \theta } \right)}^{2}}\]
    (S) \[\frac{1-\cos \theta }{1+\cos \theta }=\frac{\left( 1-\cos \theta  \right)\left( 1-\cos \theta  \right)}{\left( 1+\cos \theta  \right)\left( 1-\cos \theta  \right)}\]        
    \[=\frac{{{\left( 1-\cos \theta  \right)}^{2}}}{1-{{\cos }^{2}}\theta }\]
    \[=\frac{{{\left( 1-\cos \theta  \right)}^{2}}}{{{\sin }^{2}}\theta }\]
    \[={{\left( \frac{1-\cos \theta }{\sin \theta } \right)}^{2}}\]
    \[={{\left( \frac{1}{\sin \theta }-\frac{\cos \theta }{\sin \theta } \right)}^{2}}\]
    \[={{\left( \cos ec\theta -\cot \theta  \right)}^{2}}\]


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