10th Class Mathematics Introduction to Trigonometry Question Bank Trigonometry

  • question_answer
    The simplified value of \[{{\left( \mathbf{secx}\,\mathbf{secy}+\mathbf{tanx}\text{ }\mathbf{tany} \right)}^{2}}-{{\left( \mathbf{secx}\,\mathbf{tany}+\mathbf{tanx}\,\mathbf{secy} \right)}^{2}}\] is

    A)  -1                             

    B)  0

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

    D)  1

    Correct Answer: D

    Solution :

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


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