8th Class Mathematics Understanding Quadrilaterals Question Bank Understanding Quadrilaterals

  • question_answer
    Four of the angles of a pentagon are of equal size. The remaining angle is\[{{120}^{o}}\]. Find the value of each of the equal angles.

    A)  \[{{210}^{o}}\]                

    B)                         \[{{110}^{o}}\]

    C)                         \[{{540}^{o}}\]                

    D)                         \[{{105}^{o}}\]

    Correct Answer: D

    Solution :

    The pentagon can be divided into 3 triangles by joining the vertex A to C and D (See the figure). Angle sum of 1 triangle \[={{180}^{o}}\] Angle sum of 3 triangles                 \[=3\times {{180}^{o}}={{540}^{o}}\] Sum of the four equal angles                 \[={{540}^{o}}-{{120}^{o}}={{420}^{o}}\] Each equal angle                 \[={{420}^{o}}-4={{105}^{o}}\]


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