pentagon

the formula of a pentagon

15 in ||^  ||   || Where S is the length of a side. To find the exact area of a regular pentagon or any regular polygon, using various methods, ee [|Area of a Regular Polygon] and [|Area of an Irregular Polygon] ||
 * Interior angle || 108° || Like any regular polygon, to find the interior angle we use the formula (180n–360)/n . For a pentagon, n=5. See [|Interior Angles of a Polygon] ||
 * Exterior Angle || 72° || To find the exterior angle of a regular pentagon, we use the fact that the exterior angle forms a [|linear pair] with the interior angle, so in general it is given by the formula 180-interior angle. See [|Exterior Angles of a Polygon] ||
 * Area || 1.72 S2 approx || Example 5: ||  ||   ||
 * Solution: [[image:http://www.mathgoodies.com/lessons/vol1/images/p.gif width="25" height="23" caption="P"]] || =5(3 in)=