how to find the perimiter of a reular polygon
Anonymous has given the formula for the area of a regular polygon. If you know the area you can use that formula to find the perimeter.
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It is $${\frac{{\mathtt{1}}}{{\mathtt{2}}}}{\mathtt{\,\times\,}}\left({\mathtt{apothem}}{\mathtt{\,\times\,}}{\mathtt{perimeter}}\right)$$