10th Class Mathematics Introduction to Trigonometry Question Bank Trigonometry

  • question_answer
    The simplified value of \[\left( \mathbf{secx}\,\mathbf{secy}+\mathbf{tanx}\,\mathbf{tany} \right)-\left( \mathbf{secx}\,\mathbf{tany}+\mathbf{tanx}\,\mathbf{secy} \right)\] is

    A) \[-1\]

    B) 0

    C) \[se{{c}^{2}}x\]

    D) 1

    Correct Answer: D

    Solution :

    (d): \[{{\left( secx.secy+tanx.tany \right)}^{2}}-{{\left( secx.tany+tanx.secy \right)}^{2}}\] \[=se{{c}^{2}}x.se{{c}^{2}}y+ta{{n}^{2}}x.ta{{n}^{2}}y+\]\[2sec\,x\,.\,sec\,y\,.\,tan\,x\,.\,tan\,y-se{{c}^{2}}\] \[ta{{n}^{2}}y-ta{{n}^{2}}x\,.\,se{{c}^{2}}y-2\,sec\,x\,.\,\,secy\,.\,\,tanx\,.\text{ }tany\] \[=se{{c}^{2}}x\,.\,se{{c}^{2}}y-se{{c}^{2}}x\,.\,ta{{n}^{2}}y-ta{{n}^{2}}.\,se{{c}^{2}}y+ta{{n}^{2}}x\,.\,ta{{n}^{2}}y\] \[=se{{c}^{2}}x\left( se{{c}^{2}}y-ta{{n}^{2}}y \right)-ta{{n}^{2}}x\left( se{{c}^{2}}y-ta{{n}^{2}}y \right)\] \[=se{{c}^{2}}x-ta{{n}^{2}}x=1\]


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