Difference between revisions of "Pick's Theorem"

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It is similar to the [[Shoelace Theorem]], and although it is less powerful it is a good tool to have in solving problems.
 
It is similar to the [[Shoelace Theorem]], and although it is less powerful it is a good tool to have in solving problems.
  
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<asy>
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size(150);
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defaultpen(linewidth(0.8));
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for (int i = 1; i <= 5; i=i+1) {
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for (int j = 1; j <= 5; j=j+1) {
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dot((i,j));
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draw((1,1)--(1,3)--(3,4)--(2,5)--(5,5)--(2,2)--(4,1)--cycle);</asy>
  
 
== Proof ==
 
== Proof ==

Revision as of 21:08, 4 April 2012

Pick's Theorem expresses the area of a polygon, all of whose vertices are lattice points in a coordinate plane, in terms of the number of lattice points inside the polygon and the number of lattice points on the sides of the polygon. The formula is:

$A = I + \frac{B}{2} - 1$

where $I$ is the number of lattice points in the interior and $B$ being the number of lattice points on the boundary. It is similar to the Shoelace Theorem, and although it is less powerful it is a good tool to have in solving problems.

[asy] size(150); defaultpen(linewidth(0.8)); for (int i = 1; i <= 5; i=i+1) { for (int j = 1; j <= 5; j=j+1) { dot((i,j)); } } draw((1,1)--(1,3)--(3,4)--(2,5)--(5,5)--(2,2)--(4,1)--cycle);[/asy]

Proof

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Usage