Difference between revisions of "1993 AHSME Problems/Problem 28"

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How many triangles can be formed with vertices on a 4 by 4 grid of points?
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== Problem ==
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How many triangles with positive area are there whose vertices are points in the <math>xy</math>-plane whose coordinates are integers <math>(x,y)</math> satisfying <math>1\le x\le 4</math> and <math>1\le y\le 4</math>?
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<math>\text{(A) } 496\quad
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\text{(B) } 500\quad
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\text{(C) } 512\quad
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\text{(D) } 516\quad
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\text{(E) } 560</math>
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== Solution ==
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<math>\fbox{D}</math>
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== See also ==
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{{AHSME box|year=1993|num-b=27|num-a=29}} 
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[[Category: Intermediate Combinatorics Problems]]
 
{{MAA Notice}}
 
{{MAA Notice}}

Revision as of 02:02, 26 September 2014

Problem

How many triangles with positive area are there whose vertices are points in the $xy$-plane whose coordinates are integers $(x,y)$ satisfying $1\le x\le 4$ and $1\le y\le 4$?

$\text{(A) } 496\quad \text{(B) } 500\quad \text{(C) } 512\quad \text{(D) } 516\quad \text{(E) } 560$

Solution

$\fbox{D}$

See also

1993 AHSME (ProblemsAnswer KeyResources)
Preceded by
Problem 27
Followed by
Problem 29
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