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8th Class Mathematics Understanding Quadrilaterals Question Bank Understanding Quadrilaterals

  • question_answer
    Equilateral \[\Delta \,ABC\]is drawn on the side \[AB\] of square, ABDE. Find the measure of Y shown in the figure.

    A)  \[{{45}^{o}}\]                   

    B)                         \[{{135}^{o}}\]                

    C)                         \[{{255}^{o}}\]                

    D)                         \[{{225}^{o}}\]

    Correct Answer: C

    Solution :

    Since \[\Delta \,ABC\]is equilateral, \[\angle CBA={{60}^{o}}\] BE is the diagonal of square ABDE \[\Rightarrow \]   \[\angle ABE=\frac{{{90}^{o}}}{2}={{45}^{o}}\] Therefore, the angle marked \[x\] in the figure is \[{{360}^{o}}-({{60}^{o}}+{{45}^{o}})\] \[={{360}^{o}}-{{105}^{o}}={{255}^{o}}\]


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