document.write( "Question 393219: The vertices of triangle ABC have (x,y) coordinates (4,5), (5,3) and (1,3) respectivly. What is the area of triangle ABC?\r
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Algebra.Com's Answer #279106 by Alan3354(69443)\"\" \"About 
You can put this solution on YOUR website!
The vertices of triangle ABC have (x,y) coordinates (4,5), (5,3) and (1,3) respectivly. What is the area of triangle ABC?
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\n" ); document.write( "There's more than one way to do this, and problems like it.
\n" ); document.write( "Here's one:
\n" ); document.write( "Write the points in columns repeating the 1st point
\n" ); document.write( "A B C A
\n" ); document.write( "4 5 1 5
\n" ); document.write( "5 3 1 4
\n" ); document.write( "Add the diagonal products from upper left, then from lower left
\n" ); document.write( "Upper:
\n" ); document.write( "4*3 + 5*1 + 1*4 = 12 + 5 + 4 = 19
\n" ); document.write( "Lower:
\n" ); document.write( "5*5 + 3*1 + 1*5 = 25 + 3 + 5 = 33
\n" ); document.write( "Find the difference, 33 - 19 = 14
\n" ); document.write( "The area is 1/2 that, = 7 sq units.
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\n" ); document.write( "This method works for all polygons, any # of sides.\r
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