document.write( "Question 1040566: prove by three methods that the points (5,3), (-8,-5), (-6,-6) and (7,2) form a parallelogram?? \n" ); document.write( "

Algebra.Com's Answer #655488 by Edwin McCravy(20081) $\"\"$ $\"About$

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document.write( "There are four methods to show it:\r\n" );
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document.write( "1.  A parallelogram is a quadrilateral with both pairs of \r\n" );
document.write( "opposite sides parallel. \r\n" );
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document.write( "A. Use the slope formula to show that AB is parallel to CD\r\n" );
document.write( "B. Use the slope formula to show that BC is parallel to AD\r\n" );
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document.write( "2,  If both pairs of opposite sides of a quadrilateral are \r\n" );
document.write( "congruent, the quadrilateral is a parallelogram. \r\n" );
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document.write( "A. Use the distance formula to show that AB and CD have the \r\n" );
document.write( "same length and therefore are congruent.\r\n" );
document.write( "B. Use the distance formula to show that BC and AD have the \r\n" );
document.write( "same length and therefore are congruent.\r\n" );
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document.write( "3.  If the diagonals of a quadrilateral bisect each other, \r\n" );
document.write( "the quadrilateral is a parallelogram. \r\n" );
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document.write( "A. Use the midpoint formula to find the midpoint of diagonal AC.\r\n" );
document.write( "B. Use the midpoint formula to find the midpoint of diagonal BD \r\n" );
document.write( "to show that the two midpoints are the same.\r\n" );
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document.write( "4.  If ONE PAIR of opposite sides of a quadrilateral are BOTH \r\n" );
document.write( "parallel and congruent, the quadrilateral is a parallelogram.\r\n" );
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document.write( "If you have done both 1 and 2, you have already done enough to \r\n" );
document.write( "show that AD and BC are both parallel and congruent.\r\n" );
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document.write( "If you have trouble, tell me in the thank-you note form below and\r\n" );
document.write( "I'll get back to you by email.\r\n" );
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document.write( "Edwin

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