document.write( "Question 174494: Quadrilateral ABCD has vertices A(-1,0), B(3,3), C(6,-1), and D(2,-4). Prove that quadrilateral ABCD is a square. \n" ); document.write( "
Algebra.Com's Answer #129522 by jojo14344(1513)\"\" \"About 
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ABCD has vertices A(-1,0), B(3,3), C(6,-1), and D(2,-4)
\n" ); document.write( "Let's see 3 important properties of a Square:
\n" ); document.write( "1) All sides are EQUAL.
\n" ); document.write( "2) The Diagonals are equal.3
\n" ); document.write( "3) Each Angle is equal to 90 degress.
\n" ); document.write( ".
\n" ); document.write( "To Prove the properties, let's draw the Square first with given vertices:
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\n" ); document.write( "1) All SIDES ARE EQUAL.
\n" ); document.write( "To prove, we use distance Formula ---->\"d%5E2=%28y%5B2%5D-y%5B1%5D%29%5E2%2B%28x%5B2%5D-x%5B1%5D%29%5E2\"
\n" ); document.write( "For \"AB\":
\n" ); document.write( "
\n" ); document.write( "\"d%5BAB%5D=sqrt%2825%29=highlight%285=d%5BAB%5D%29\"
\n" ); document.write( "For \"BC\":
\n" ); document.write( "\"d%5BBC%5D%5E2=%28-1-3%29%5E2%2B%286-3%29%5E2=%28-4%5E2%2B3%5E2%29=16%2B9\"
\n" ); document.write( "\"d%5BBC%5D=sqrt%2825%29=highlight%285=d%5BBC%5D%29\"
\n" ); document.write( "For \"CD\":
\n" ); document.write( "
\n" ); document.write( "\"d%5BCD%5D=sqrt%2825%29=highlight%285=d%5BCD%5D%29\"
\n" ); document.write( "For \"AD\"
\n" ); document.write( "\"d%5BAD%5D%5E2=%28-4-0%29%5E2%2B%282-%28-1%29%29%5E2=-4%5E2%2B%28-3%29%5E2=16%2B9\"
\n" ); document.write( "\"d%5BAD%5D=sqrt%2825%29=highlight%285=d%5BAD%5D%29\"
\n" ); document.write( ".
\n" ); document.write( "Therefore, you can see all SIDES are EQUAL IN LENGTH,\"d%5BAB%5D=d%5BBC%5D=d%5BCD%5D=d%5BAD%5D=5\"
\n" ); document.write( "It follows, as you see in the graph:
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\n" ); document.write( ".
\n" ); document.write( "2) The Diagonals are EQUAL.
\n" ); document.write( "The diagonals here are referred to \"BD\" adn \"AC\". And again we use Distance formula, \"d%5E2=%28y%5B2%5D-y%5B1%5D%29%5E2%2B%28x%5B2%5D-x%5B1%5D%29%5E2\"
\n" ); document.write( "For \"BD\":
\n" ); document.write( "\"d%5BBD%5D%5E2=%28-4-3%29%5E2%2B%282-3%29%5E2=-7%5E2%2B-1%5E2=49%2B1\"
\n" ); document.write( "\"highlight%28d%5BBD%5D=sqrt%2850%29%29\"
\n" ); document.write( "For \"AC\";
\n" ); document.write( "\"d%5BAC%5D=%28-1-0%29%5E2%2B%286-%28-1%29%29%5E2=-1%5E2%2B%286%2B1%29%5E2=-1%5E2%2B7%5E2\"
\n" ); document.write( "\"highlight%28d%5BAC%5D=sqrt%2850%29%29\"
\n" ); document.write( "Therefore: \"d%5BBD%5D=d%5BAC%5D=sqrt%2850%29\"
\n" ); document.write( "It satisfy the 2nd property, and as we see in the graph:
\n" ); document.write( "
\n" ); document.write( ".
\n" ); document.write( "3) Each Angle is equal to 90 DEGREES
\n" ); document.write( "In this property we use Equation for Right Traingles, the Pythagorean theorem.
\n" ); document.write( "Just where the formula we used above is derived from.
\n" ); document.write( "For Triangle \"ABC\":
\n" ); document.write( "\"AC%5E2=AB%5E2%2BBC%5E2\"
\n" ); document.write( "\"AC%5E2=5%5E2%2B5%5E2\"
\n" ); document.write( "\"AC%5E2=25%2B25\"
\n" ); document.write( "\"AC=sqrt%2850%29=DIAGONAL\", A Right Triangle!
\n" ); document.write( "For Triangle \"BCD\":
\n" ); document.write( "\"BD%5E2=BC%5E2%2BCD%5E2\"
\n" ); document.write( "\"BD%5E2=5%5E2%2B5%5E2=25%2B25\"
\n" ); document.write( "\"BD=sqrt%2850%29=DIAGONAL\", A Right Triangle!
\n" ); document.write( "For Triangle \"CDA\"
\n" ); document.write( "\"AC%5E2=AD%5E2%2BCD%5E2\"
\n" ); document.write( "\"AC%5E2=5%5E2%2B5%5E2=25%2B25\"
\n" ); document.write( "\"AC=sqrt%2850%29=DIAGONAL\", A Right Triangle
\n" ); document.write( "For Triangle \"DAB\"
\n" ); document.write( "\"BD%5E2=AD%5E2%2BAB%5E2\"
\n" ); document.write( "\"BD%5E2=5%5E2%2B5%5E2=25%2B25\"
\n" ); document.write( "\"BD=sqrt%2850%29=DIAGONAL\", A Right Triangle!
\n" ); document.write( "ALL satisfies the Pythagorean theorem, therefore all angles are 90 degrees:
\n" ); document.write( ".
\n" ); document.write( "Conclusion: ABCD that has vertices A(-1,0), B(3,3), C(6,-1), and D(2,-4) is a SQUARE.
\n" ); document.write( "Thank you,
\n" ); document.write( "Jojo
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