SOLUTION: the number of diagonal of a regular polygon is779.find how many side it has

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Question 1005637: the number of diagonal of a regular polygon is779.find how many side it has


Answer by jim_thompson5910(35256)   (Show Source): You can put this solution on YOUR website!
d = number of diagonals
n = number of sides

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In this case,
d = 779
n = unknown (we're solving for this)

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We will use the formula
Plug in and solve for n





Multiply both sides by 2





Subtract 1558 from both sides





Use the quadratic formula to find that or .

Ignore since it doesn't make sense to have a negative number of diagonals.

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The only solution is

There are 41 sides.

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