Circumscribed and inscribed circles of a regular hexagon?

Click For Summary

Discussion Overview

The discussion revolves around calculating the ratio of the areas of the circumscribed and inscribed circles of a regular hexagon. Participants explore the geometric properties of the hexagon, including the relationships between its sides and the circles associated with it, with a focus on deriving these relationships from first principles.

Discussion Character

  • Exploratory
  • Mathematical reasoning

Main Points Raised

  • One participant asks for help in determining the ratio of the areas of the circumscribed and inscribed circles of a regular hexagon and seeks guidance on how to approach the problem from first principles.
  • Another participant provides a formula for the apothem of a regular polygon and discusses the calculation of the inner angle, suggesting that the definitions of circumscribed and inscribed circles may be confused.
  • A participant notes that the regular hexagon can be divided into six equilateral triangles, indicating that the radius of the inscribed circle corresponds to the height of one triangle, while the radius of the circumscribed circle is equal to the side length of the triangle.
  • One participant claims that the ratio of the radii of the circles is equal to the tangent of 30 degrees, although this assertion is not elaborated upon.
  • Another participant attempts to derive the areas of the circumscribed and inscribed circles using the Pythagorean theorem, providing a calculation that involves the height of the triangle and the side length.

Areas of Agreement / Disagreement

There is no consensus on the final ratio of the areas or the methods to derive it, as participants present different approaches and interpretations of the geometric properties involved.

Contextual Notes

The discussion includes various mathematical steps and assumptions that may not be fully resolved, such as the definitions of the terms used and the calculations of areas based on the derived relationships.

josephcollins
Messages
59
Reaction score
0
Hey ppl,
Could anyone help me with this: what is the ratio of the areas of the circumscribed and inscribed circles of a regular hexagon? how do I go about working it out from first principles?
Cheers, joe
 
Mathematics news on Phys.org
Well for any regular polygon its "apotema" (apothem perhaps?) is

[tex]a = \frac{L}{2}tan \frac{\alpha}{2}[/tex]

where [tex]L[/tex] is the length of a side and [tex]\alpha[/tex] is the inner angle of the polygon.

To calculate this inner angle just use the formula

[tex]\alpha = \frac{(n-2)180}{n}[/tex]

where n is the number of sides

and its Area is

[tex]A = \frac{1}{2}pa[/tex]

where p is the perimeter or nL

Now if i remember circumscribed correctly means a circle inside the hexagone and inscribed means a hexagone inside the circle, right?

maybe this could be calculated with right triangles...anyhow the formulas above could help you for a regular hexagone

Edit: sorry for so many edits, seems i need a break.
 
Last edited:
The regular hexagon consists of six equilateral triangles, the radius of the inscribed circle is equal to the height (i.e. distance from top to middle of base) of one such triangle and the radius of the circumscribed circle is equal to the length of a side of one such triangle.
 
In other words, the ratio of radii is clearly equal to the tangent of 30[/color].
 
Gokul43201 said:
In other words, the ratio of radii is clearly equal to the tangent of 30[/color].

Or you just use phytagoras to see that:

heigth^2 + (1/2 * side)^2 = side^2
heigth^2 = side^2 - 1/4 * side^2
height^2 = 3/4 * side^2

and then:

area of circumscibed circle:
2Pi * side^2
area of inscribed circle:
2Pi * 3/4 * side^2

[/color].
 

Similar threads

  • · Replies 9 ·
Replies
9
Views
2K
  • · Replies 3 ·
Replies
3
Views
4K
  • · Replies 1 ·
Replies
1
Views
7K
  • · Replies 7 ·
Replies
7
Views
6K
  • · Replies 4 ·
Replies
4
Views
2K
  • · Replies 1 ·
Replies
1
Views
3K
Replies
4
Views
4K
  • · Replies 7 ·
Replies
7
Views
2K
  • · Replies 13 ·
Replies
13
Views
3K
  • · Replies 1 ·
Replies
1
Views
6K