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a diagonal of a polygon is a straight line joining any 2 non-adjacent corners.a decagon has 10 corners. .how many diagonals does it have ?

  • math -

    Joining any two points will produce a line
    there are C(10,2) such lines or 45 of them
    But, 10 of them will be the actual sides of the polygon, the others are diagonals

    number of diagonals = 45-10 = 35

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    thanks for your kindness

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