document.write( "Question 242792: Always, sometimes, or never; If the opposite angles of a quadrilateral are supplementary, the quadrilateral is a parallelogram \n" ); document.write( "
Algebra.Com's Answer #177752 by Edwin McCravy(20060)\"\" \"About 
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Always, sometimes, or never; If the opposite angles of a quadrilateral are supplementary, the quadrilateral is a parallelogram.
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document.write( "When and only when the quadrilateral is a parallelogram which is also \r\n" );
document.write( "a rectangle and the opposite angles are both 90°. Two right angles\r\n" );
document.write( "are supplementary.\r\n" );
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document.write( "So the answer is \"sometimes\".\r\n" );
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document.write( "Edwin
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