document.write( "Question 135147: Prove that the triangle with vertices(13,-1),(-9,3),(-3,-9) is a right triangle. \n" ); document.write( "
Algebra.Com's Answer #99084 by Fombitz(32388)\"\" \"About 
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Let's name the points
\n" ); document.write( "A (13,-1)
\n" ); document.write( "B (-9,3)
\n" ); document.write( "C (-3,-9)
\n" ); document.write( "For a right triangle the sums of the squares of the two legs equal the square of the hypotenuse, the longest leg.
\n" ); document.write( "Calculate each leg length first using the distance formula between two points.
\n" ); document.write( "\"D%5E2=%28x%5B1%5D-x%5B2%5D%29%5E2%2B%28y%5B1%5D-y%5B2%5D%29%5E2\"
\n" ); document.write( "AB, the distance from point A to point B.
\n" ); document.write( "\"%28AB%29%5E2=%2813-%28-9%29%29%5E2%2B%28-1-3%29%5E2\"
\n" ); document.write( "\"%28AB%29%5E2=%2822%29%5E2%2B%284%29%5E2\"
\n" ); document.write( "\"%28AB%29%5E2=484%2B16\"
\n" ); document.write( "\"%28AB%29%5E2=500\"
\n" ); document.write( "AC, the distance from point A to point C.
\n" ); document.write( "\"%28AC%29%5E2=%2813-%28-3%29%29%5E2%2B%28-1-%28-9%29%29%5E2\"
\n" ); document.write( "\"%28AC%29%5E2=%2816%29%5E2%2B%288%29%5E2\"
\n" ); document.write( "\"%28AC%29%5E2=256%2B64\"
\n" ); document.write( "\"%28AC%29%5E2=320\"
\n" ); document.write( "BC, the distance from point B to point C.
\n" ); document.write( "\"%28BC%29%5E2=%28-9-%28-3%29%29%5E2%2B%283-%28-9%29%29%5E2\"
\n" ); document.write( "\"%28BC%29%5E2=%28-6%29%5E2%2B%2812%29%5E2\"
\n" ); document.write( "\"%28BC%29%5E2=36%2B144\"
\n" ); document.write( "\"%28BC%29%5E2=180\"
\n" ); document.write( "Since AB is the largest, it is the hypotenuse.
\n" ); document.write( "If it is a right triangle then,
\n" ); document.write( "\"%28AB%29%5E2=%28AC%29%5E2%2B%28BC%29%5E2\"
\n" ); document.write( "\"500=320%2B180\"
\n" ); document.write( "\"500=500\"
\n" ); document.write( "True statement.
\n" ); document.write( "Those point, therefore, define a right triangle.
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