10th Class Mathematics Coordinate Geometry Question Bank Co-ordinate Geometry

  • question_answer
    The distance between the point \[(a\,cos\,\theta +b\,sin\,\theta ,\,0)\]and \[(0,\,\,a\,\sin \,\theta -b\,\cos \,\theta )\] is___.

    A)  \[{{a}^{2}}+{{b}^{2}}\]                 

    B)  \[a+b\]

    C)  \[\sqrt{{{a}^{2}}-{{b}^{2}}}\]                     

    D)  \[\sqrt{{{a}^{2}}+{{b}^{2}}}\]

    Correct Answer: D

    Solution :

    (d): Distance =\[\sqrt{{{(a\,\,cos\,\,\theta +b\,\,\sin \,\,\theta -0)}^{2}}+{{(0-a\,\,sin\,\,\theta +b\,\,\cos \,\,\theta )}^{2}}}\] \[=\sqrt{{{a}^{2}}\,{{\cos }^{2}}\theta +{{b}^{2}}{{\sin }^{2}}\theta +2ab\,\cos \,\theta \,\sin \,\theta +{{b}^{2}}\,{{\cos }^{2}}\theta +{{a}^{2}}{{\sin }^{2}}\theta -2ab\,\sin \theta \,\cos \,\theta }\] \[=\sqrt{{{a}^{2}}+{{b}^{2}}}\]


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