The sum of the interior angles of a polygon with [tex]n[/tex] sides is
[tex]180(n-2)[/tex]
Since a pentagon has 5 sides, the sum of its interior angles is
[tex] 180(5-2) = 180 \cdot 3 = 540 [/tex]
Since it is a regular pentagon, all sides and angles are the same, so one single angle measures
[tex] \dfrac{540}{5} = 108 [/tex] degrees.
