194 Part 3: The Shape of the World
CHECK POINT- Find the number of diagonals in an octagon (8 sides).
- Find the total of the measures of all the interior angles in a nonagon (9 sides).
- If a hexagon is regular, find the measure of any one of its interior angles.
- If the interior angles of a polygon add up to 900r, how many sides does the
polygon have? - If a polygon has a total of 119 possible diagonals, how many sides does it have?
Area of Regular Polygons
When it comes to the area of polygons with more than four sides, there aren’t a lot of rules you
can follow. In most cases, you have to find a way to break the polygon up into smaller polygons,
maybe triangles, find the area of those and add them all up. It’s something, but most times you
won’t have the information you need to find all those areas.
There is one situation where you can follow a rule, and that’s when you’re looking for the area of
a regular polygon. A regular polygon is one that is equilateral and equiangular. It has sides that are
all the same length and angles that are all the same size.DEFINITION
A polygon is regular if all sides are the same length and all angles are congruent.radiusapothemsidehalf of
a side