Tony is drawing a regular polygon. He has drawn two of the sides with an interior angle of 120°, as shown below. What will be the sum of the interior angles of the regular polygon have when Tony completes his drawing?

Question

Tony is drawing a regular polygon. He has drawn two of the sides with an interior angle of 120°, as shown below.  What will be the sum of the interior angles of the regular polygon have when Tony completes his drawing?

anonymous · Answer

each interior angle =180 -360/n   (n number of sides)
here 120=180 -360/n 
or 360/n =60
hence n=6
the sum of the interior angles of the regular polygon have when Tony completes his drawing
=180((6-2) =720