9th Class Mathematics Quadrilaterals Question Bank Quadrilaterals

  • question_answer
    By using a given figure of quadrilateral ABCD, match the following:
    Column-I                         Column-II
    (p) (P) If ABCD is a  parallelogram, then sum of the angles  x, y and z is (1) \[{{25}^{o}}\]                
    (q) (Q) If ABCD is a rhombus, where  \[\angle D={{130}^{o}},\]then the value of \[x\]is (2) \[{{180}^{o}}\]    
    (r) (R) If ABCD is a  rhombus, the  value of w is (3) \[{{50}^{o}}\]    
    (s) (S) If ABCD is a  parallelogram, where\[x+y={{130}^{o}}\]  then the value of B is (4) \[{{90}^{o}}\]              

    A) \[(p)\to (1),(q)\to (2),(r)\to (3),(s)\to (4)\]

    B)        \[(p)\to (2),(q)\to (1),(r)\to (4),(s)\to (3)\]

    C)        \[(p)\to (3),(q)\to (1),(r)\to (2),(s)\to (4)\]

    D)        \[(p)\to (4),(q)\to (3),(r)\to (1),(s)\to (2)\]

    Correct Answer: C

    Solution :

    (P) In \[\Delta ABC,\]by angle sum property \[x+y+\angle ABC={{180}^{o}}\] \[\Rightarrow \]\[\angle ABC={{180}^{o}}-(x+y)\]           ?(i) \[\therefore \]\[\angle ABC=\angle ADC\] [\[\because \]Opposite angles of a parallelogram are equal] \[\therefore \] \[z={{180}^{o}}-(x+y)\]               [using (i)] \[\Rightarrow \]\[x+y+z={{180}^{o}}\] \[(Q)\angle C=2x\] [Since, diagonals bisects the angles in rhombus] Now, we have \[\angle D+\angle C={{180}^{o}}\]       [Co-interior angles] \[{{130}^{o}}+2x={{180}^{o}}\]      \[(\angle D={{130}^{o}})\] \[\Rightarrow \]\[2x={{180}^{o}}-{{130}^{o}}={{50}^{o}}\Rightarrow x={{25}^{o}}\] (R) Since, in a rhombus, diagonals bisect each other. \[\therefore \]      \[w={{90}^{o}}\] (S) Since in a parallelogram opposite angles are equal. \[\therefore \] \[\angle B=\angle D=z\]                                           ?(i) In\[\Delta \Alpha \Beta C,\]by angle sum property, \[\angle B+x+y={{180}^{o}}\] \[\angle B={{180}^{o}}-(x+y)\] \[\therefore \]\[z={{180}^{o}}-(x+y)\]    (using (i)) \[={{180}^{o}}-{{130}^{o}}={{50}^{o}}\]


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