<?php
$page_name = "Center Circle Size";
$menu_type = "erudition";
$menu_name = "Circles";
$blog_num = 64;
$page_rate = 8;
$page_tags = array("random");
$page_date = "January 7, 2012";
include_once("./files/head.php");

echo "<div class=\"leftpic\"><img src=\"./images/knowledge/circles_01.gif\" width=85 height=77></div>\n";
echo "<p>Random math patterns time.  If you take a quarter, or any other coin, you can fit 6 other coins around it so they are all touching the center coin and their neighbors on either side.  Why 6? I dunno.  But what size does the middle one have to be for 5 outside circles? or 4?</p>\n";

echo "<h3>Start</h3>\n";
echo "<div class=\"leftpic\"><img src=\"./images/knowledge/circles_02.gif\" width=120 height=120></div>\n";
echo "<p>So lets assume the radius of the circles on the outside (our quarters) is 1.  A quarter is 2 quarter-radius' in diameter...go figure.</p>\n";
echo "<p>If you draw a line between the centers of our circles you will get a bunch of angles.  In the case of our 6 quarters, we get a hexagon.";
echo "<br />The sum of the outer angles for a polygon is &#8721;a = 180*(n-2), so for a hexagon we get 720 degrees, or 120 degrees for each angle.";
echo "<br />Now if you draw a 2 lines from the center of 2 next door circles into the center you get a triangle.  Each of the 2 outer angles will be half the original outer angle (120/2 = 60) and the center will be 180 minus the sum of the 2 angles (180-60-60=60).";
echo "<br />So, how can we compare the number of outer circles to the inner angles?</p>\n";
echo "<h3 class=\"equation\">inner angle = 180 - (2 * ( &#8721;a / 2 ) / x)";
echo "<br />or simplified:&nbsp;&nbsp;&nbsp;inner angle = 180 - ( &#8721;a / x )</h3>";

echo "<p>So then we can calculate out for each shape:</p>\n";
echo "<center>\n";
echo "<table>\n";
  echo "<tr>\n";
    echo "<th># of Outer Circles</th>\n";
    echo "<th>Internal Angle</th>\n";
  echo "</tr>\n";
  echo "<tr>\n";
    echo "<td>3</td>\n";
    echo "<td>120</td>\n";
  echo "</tr>\n";
  echo "<tr>\n";
    echo "<td>4</td>\n";
    echo "<td>90</td>\n";
  echo "</tr>\n";
  echo "<tr>\n";
    echo "<td>5</td>\n";
    echo "<td>72</td>\n";
  echo "</tr>\n";
  echo "<tr>\n";
    echo "<td>6</td>\n";
    echo "<td>60</td>\n";
  echo "</tr>\n";
  echo "<tr>\n";
    echo "<td>8</td>\n";
    echo "<td>45</td>\n";
  echo "</tr>\n";
echo "</table>\n";
echo "</center>\n";

echo "<h3>Inner Circle Diameter</h3>\n";
echo "<p>Now, how do we relate the inner angle to the radius of the middle circle?";
echo "<br />Something like this:</p>\n";
echo "<h3 class=\"equation\">inner radius = outer radius / ( SIN( inner angle / 2 ) - outer radius";
echo "<br />with numbers:&nbsp;&nbsp;&nbsp;inner radius = 1 / ( SIN( inner angle / 2 ) - 1</h3>";

echo "<p>So:</p>\n";
echo "<center>\n";
echo "<table>\n";
  echo "<tr>\n";
    echo "<th># of Outer Circles</th>\n";
    echo "<th>Internal Angle</th>\n";
    echo "<th>Internal Radius</th>\n";
    echo "<th>Internal Diameter</th>\n";
  echo "</tr>\n";
  echo "<tr>\n";
    echo "<td>3</td>\n";
    echo "<td>120</td>\n";
    echo "<td>0.155</td>\n";
    echo "<td>0.309</td>\n";
  echo "</tr>\n";
  echo "<tr>\n";
    echo "<td>4</td>\n";
    echo "<td>90</td>\n";
    echo "<td>0.414</td>\n";
    echo "<td>0.828</td>\n";
  echo "</tr>\n";
  echo "<tr>\n";
    echo "<td>5</td>\n";
    echo "<td>72</td>\n";
    echo "<td>0.701</td>\n";
    echo "<td>1.403</td>\n";
  echo "</tr>\n";
  echo "<tr>\n";
    echo "<td>6</td>\n";
    echo "<td>60</td>\n";
    echo "<td>1.000</td>\n";
    echo "<td>2.000</td>\n";
  echo "</tr>\n";
  echo "<tr>\n";
    echo "<td>8</td>\n";
    echo "<td>45</td>\n";
    echo "<td>1.613</td>\n";
    echo "<td>2.610</td>\n";
  echo "</tr>\n";
echo "</table>\n";
echo "</center>\n";

echo "<h3>And This Affects Me How?</h3>\n";
echo "<p>Hopefully not at all really.  But according to wikipedia and some quicky ratio-ization lets have some fun:</p>\n";
echo "<center>\n";
echo "<table>\n";
  echo "<tr>\n";
    echo "<th>Coin</th>\n";
    echo "<th>Diameter</th>\n";
    echo "<th>Circle Design</th>\n";
  echo "</tr>\n";
  echo "<tr>\n";
    echo "<td>Penny</td>\n";
    echo "<td>19.05</td>\n";
    echo "<td>6 outer : 1 inner</td>\n";
  echo "</tr>\n";
  echo "<tr>\n";
    echo "<td>Nickle</td>\n";
    echo "<td>21.20</td>\n";
    echo "<td>6 outer : 1 inner</td>\n";
  echo "</tr>\n";
  echo "<tr>\n";
    echo "<td>Dime</td>\n";
    echo "<td>18.03</td>\n";
    echo "<td>6 outer : 1 inner</td>\n";
  echo "</tr>\n";
  echo "<tr>\n";
    echo "<td>Quarter</td>\n";
    echo "<td>23.88</td>\n";
    echo "<td>6 outer : 1 inner</td>\n";
  echo "</tr>\n";
  echo "<tr>\n";
    echo "<td>50 cent</td>\n";
    echo "<td>27.13</td>\n";
    echo "<td>6 outer : 1 inner<br />5 outer : 1 inner penny</td>\n";
  echo "</tr>\n";
  echo "<tr>\n";
    echo "<td>Loonie</td>\n";
    echo "<td>26.50</td>\n";
    echo "<td>6 outer : 1 inner<br />5 outer : 1 inner dime (close)</td>\n";
  echo "</tr>\n";
  echo "<tr>\n";
    echo "<td>Toonie</td>\n";
    echo "<td>28.00</td>\n";
    echo "<td>6 outer : 1 inner<br />5 outer : 1 inner penny (close)</td>\n";
  echo "</tr>\n";
echo "</table>\n";
echo "</center>\n";
echo "<p>Well that was really an excersize in letdown...oh well, my questions were answered, and your time wasted, so 2 points to me!</p>\n";


include_once("./files/close.php");
?>