document.write( "Question 981273: How many equilateral triangles in the plane have two vertices in the set {(0,0), (0,1), (1,0), (1,1)}?
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Algebra.Com's Answer #602288 by Edwin McCravy(20056) $\"\"$ $\"About$

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document.write( "Given two points, two equilateral triangles can be\r\n" );
document.write( "drawn having those two points as vertices.\r\n" );
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document.write( "There are 4 points, so there are C(4,2) = 4C2 = 6 pairs of \r\n" );
document.write( "points and since two equilateral triangles can be drawn having\r\n" );
document.write( "that pair of points as vertices, there are 12 equilateral \r\n" );
document.write( "triangles that can be drawn having two vertices in the set \r\n" );
document.write( "{(0,0), (0,1), (1,0), (1,1)}.\r\n" );
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document.write( "Answer: 12\r\n" );
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document.write( "Here are the 8 equilateral triangles using the sides of the square as vertices:\r\n" );
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document.write( "Here are the 4 equilateral triangles using the 2 diagonals \r\n" );
document.write( "of the square as a side.\r\n" );
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document.write( "Here are all 12, all black:\r\n" );
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document.write( "Edwin

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