document.write( "Question 947878: The difference between exterior angles of a \"n\" sided regular polygon and \"n+1\" sided regular polygon is 12 degrees. Find value of \"n\" \r
\n" ); document.write( "\n" ); document.write( "Regards
\n" ); document.write( "Vidhu
\n" ); document.write( "

Algebra.Com's Answer #578502 by KMST(5328)\"\" \"About 
You can put this solution on YOUR website!
The sum of the measures of the exterior angles of a convex polygon is always \"360%5Eo\" .
\n" ); document.write( "(The exterior angles are the angles of change of direction you must make at each corner (vertex) as you go around along the perimeter of the polygon, so of course
\n" ); document.write( "a whole turn around the polygon will shift your direction by \"360%5Eo\" to end in the same direction you started).
\n" ); document.write( "In a regular polygon with \"n\" sides there are \"n\" congruent exterior angles, all with the same measure: \"360%5Eo%2Fn\" .
\n" ); document.write( "Similarly, the measure of each exterior angle of an \"n%2B1\" sided polygon is \"360%5Eo%2F%28n%2B1%29\" ,
\n" ); document.write( "which is smaller than \"360%5Eo%2Fn\" by
\n" ); document.write( "\"360%5Eo%2Fn-360%5Eo%2F%28n%2B1%29\" .
\n" ); document.write( "For this problem,
\n" ); document.write( "\"12%5Eo=360%5Eo%2Fn-360%5Eo%2F%28n%2B1%29\"
\n" ); document.write( "\"12%5Eo=360%5Eo%281%2Fn-1%2F%28n%2B1%29%29\"
\n" ); document.write( "Dividing both sides of the equal sign by \"12%5Eo\" we get
\n" ); document.write( "\"1=30%281%2Fn-1%2F%28n%2B1%29%29\"
\n" ); document.write( "\"1=30%28%28n%2B1%29%2F%28n%28n%2B1%29%29-n%2F%28n%28n%2B1%29%29%29\"
\n" ); document.write( "\"1=30%28%28n%2B1-n%29%2F%28n%28n%2B1%29%29%29\"
\n" ); document.write( "\"1=30%2F%28n%28n%2B1%29%29\"
\n" ); document.write( "Multiplying both sides of the equal sign times \"n%28n%2B1%29\" we get
\n" ); document.write( "\"n%28n%2B1%29=30\"
\n" ); document.write( "We can say that the above equation is a quadratic equation,
\n" ); document.write( "and we know that a quadratic equation can have at most two solutions.
\n" ); document.write( "We could go through all kinds of algebra efforts to solve that equation,
\n" ); document.write( "but we all know that \"5%2A6=30\" and that \"%28-6%29%2A%28-5%29=30\" ,
\n" ); document.write( "so we know that the two solutions are \"highlight%28n=5%29\" and \"n=-6\" .
\n" ); document.write( "(We also know that \"n\" must be an integer greater than \"2\" ,
\n" ); document.write( "because a polygon must have \"3\" or more sides,
\n" ); document.write( "so \"n=-6\" makes no sense).
\n" ); document.write( "
\n" );