document.write( "Question 824253: Prove that a quadrilateral ABCD with vertices A(-1,4), B(-3,3), C(1,2) and D(3,3) is a parallelogram \n" ); document.write( "
Algebra.Com's Answer #496247 by richwmiller(17219)\"\" \"About 
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quadrilateral
\n" ); document.write( "edge lengths
\n" ); document.write( "| (sqrt(5) | sqrt(17) | sqrt(5) | sqrt(17))
\n" ); document.write( "=(2.23607 | 4.12311 | 2.23607 | 4.12311)
\n" ); document.write( "diagonal lengths
\n" ); document.write( "| (2 sqrt(2) | 6)
\n" ); document.write( "=(2.82843 | 6)
\n" ); document.write( "area | 6
\n" ); document.write( "perimeter | 2 (sqrt(5)+sqrt(17))=12.7183
\n" ); document.write( "interior angles
\n" ); document.write( "| ((180 (pi-tan^(-1)(1/4)-tan^(-1)(1/2)))/pi° | (180 (tan^(-1)(1/4)+tan^(-1)(1/2)))/pi° | (180 (pi-tan^(-1)(1/4)-tan^(-1)(1/2)))/pi° | (180 (tan^(-1)(1/4)+tan^(-1)(1/2)))/pi°)=
\n" ); document.write( "(2.43297 radians | 0.708626 radians | 2.43297 radians | 0.708626 radians)
\n" ); document.write( "interior angle sum | 360° = 2 pi rad
\n" ); document.write( "exterior angle sum | 1080° = 6 pi rad\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "| (-1, 4) | (-3, 3) | (1, 2) | (3, 3)
\n" ); document.write( "(-1, 4) | 0 | sqrt(5)=2.23607 | 2 sqrt(2)~~2.82843 | sqrt(17)~~4.12311
\n" ); document.write( "(-3, 3) | sqrt(5)~~2.23607 | 0 | sqrt(17)~~4.12311 | 6
\n" ); document.write( "(1, 2) | 2 sqrt(2)~~2.82843 | sqrt(17)~~4.12311 | 0 | sqrt(5)~~2.23607
\n" ); document.write( "(3, 3) | sqrt(17)~~4.12311 | 6 | sqrt(5)~~2.23607 | 0 \n" ); document.write( "
\n" );