document.write( "Question 143400This question is from textbook CPM
\n" ); document.write( ": how many sides does a polygon have if the sum of its interior angles is 1440 degress \n" ); document.write( "

Algebra.Com's Answer #104367 by Earlsdon(6294) $\"\"$ $\"About$

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You haven't indicated whether or not this is a REGULAR polygon (one whose sides are all of equal length) but I'll assume that it is.
\n" ); document.write( "You can start with the formula for the sum of the interior angles (S) of a regular polygon of n-sides:
\n" ); document.write( " $\"S+=+%28n-2%29180\"$ Since you know that this sum is 1440 degrees, you can substitute this into the formula and solve for n, the number of sides.
\n" ); document.write( " $\"1440+=+%28n-2%29180\"$ Divide both sides by 180
\n" ); document.write( " $\"8+=+n-2\"$ Add 2 to both sides.
\n" ); document.write( " $\"n+=+10\"$
\n" ); document.write( "The regular polygon has 10 sides. This is known as a decagon. \n" ); document.write( "

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