Math Problem Statement

The value of x so that every regular polygon with more sides has non-integer interior angles

Solution

To find the value of xx, where xx is the number of sides of a regular polygon such that every polygon with more sides has non-integer interior angles, we need to look at the formula for the interior angle of a regular polygon.

The interior angle AA of a regular polygon with nn sides is given by:

A=(n2)180nA = \frac{(n-2) \cdot 180^\circ}{n}

For every regular polygon with more than xx sides to have a non-integer interior angle, we want to find the largest integer xx such that the interior angle is still an integer.

  1. Set the formula for the interior angle AA to be an integer. This implies that the expression

(n2)180n\frac{(n-2) \cdot 180}{n}

must be an integer for n=xn = x.

  1. Now, let's check small values of nn to find the point at which this no longer results in an integer:

    • For n=3n = 3 (triangle): A=(32)1803=60(integer)A = \frac{(3-2) \cdot 180}{3} = 60^\circ \quad \text{(integer)}
    • For n=4n = 4 (square): A=(42)1804=90(integer)A = \frac{(4-2) \cdot 180}{4} = 90^\circ \quad \text{(integer)}
    • For n=5n = 5 (pentagon): A=(52)1805=108(integer)A = \frac{(5-2) \cdot 180}{5} = 108^\circ \quad \text{(integer)}
    • For n=6n = 6 (hexagon): A=(62)1806=120(integer)A = \frac{(6-2) \cdot 180}{6} = 120^\circ \quad \text{(integer)}
    • For n=7n = 7 (heptagon): A=(72)1807128.57(non-integer)A = \frac{(7-2) \cdot 180}{7} \approx 128.57^\circ \quad \text{(non-integer)}

Thus, the first polygon with a non-integer interior angle is the regular heptagon with n=7n = 7 sides. So, the value of xx is 6. Any regular polygon with more than 6 sides will have a non-integer interior angle.

Would you like more details or have any questions?

Here are 5 related questions you might find interesting:

  1. How do exterior angles of polygons relate to their interior angles?
  2. What is the sum of interior angles for any nn-sided polygon?
  3. Can the interior angle of a polygon ever be 180 degrees? Why or why not?
  4. What is the formula for the area of a regular polygon in terms of its side length and number of sides?
  5. How do the number of sides of a polygon affect the ratio of its perimeter to its area?

Tip: The sum of the exterior angles of any regular polygon is always 360360^\circ, no matter the number of sides.

Ask a new question for Free

By Image

Drop file here or Click Here to upload

Math Problem Analysis

Mathematical Concepts

Geometry
Polygons
Interior Angles

Formulas

Interior angle formula for regular polygons: A = ((n-2) * 180) / n

Theorems

Polygon angle sum theorem: The sum of interior angles of an n-sided polygon is (n-2) * 180

Suitable Grade Level

Grades 8-10