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

  • question_answer
    In figure, \[\text{AD}=\text{4}\,\text{cm},\] \[\text{BD}=\text{3 cm}\] and \[\text{CB}=\text{12 cm},\]then the value of \[\cot \theta \] is:(CBSE 2016)

    A) \[\frac{5}{12}\]

    B) \[\frac{12}{5}\]

    C) \[\frac{7}{5}\]

    D) \[\frac{5}{7}\]

    Correct Answer: B

    Solution :

    [b] In right-angled \[\Delta ADB.\]
    \[A{{B}^{2}}=B{{D}^{2}}+A{{D}^{2}}\]
    \[={{(3)}^{2}}+{{(4)}^{2}}\]  (By Pythagoras theorem)
    \[=9+16=25\]
    \[\therefore \,\,\,\,\,\,\,\,\,\,\,\,\,\,AB=5cm\]
    Now, in right-angled \[\Delta ABC\]
    \[\cot \theta =\frac{BC}{AB}=\frac{12}{5}\]


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