document.write( "Question 1137650: Determine the coordinates of the orthocentre of triangle DEF with vertices at D (-3,4) E (8,-2) F (4,5) \n" ); document.write( "
Algebra.Com's Answer #755583 by MathLover1(20850)\"\" \"About 
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\n" ); document.write( "given: \"DEF\" with vertices at
\n" ); document.write( "\"D\" (\"-3\",\"4\")
\n" ); document.write( "\"E\" (\"8\",\"-2\")
\n" ); document.write( "\"F\" (\"4\",\"5\") \r
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\n" ); document.write( "\n" ); document.write( "the orthocenter: the point where the three \"altitudes\" of a triangle meet\r
\n" ); document.write( "\n" ); document.write( "find the slopes of the lines that contain segments \"DE\" and\"+EF\" \r
\n" ); document.write( "\n" ); document.write( "slope of \"DE+=+%28-2-4%29%29%2F%288-%28-3%29%29+=+-6%2F11+\"\r
\n" ); document.write( "\n" ); document.write( "now, we need a slope of perpendicular line, altitude to segments \"DE\":\r
\n" ); document.write( "\n" ); document.write( "slope of perpendicular line, altitude : \"-1%2Fm+=+-1%2F%28-6%2F11%29\" -> \"m+=+11%2F6\"\r
\n" ); document.write( "\n" ); document.write( "\"y+=+mx+%2B+b\" (substitute \"m+=+11%2F6\", \"x+=+4\", \"y+=+5\")\r
\n" ); document.write( "\n" ); document.write( "\"5+=+%2811%2F6%29%284%29+%2B+b\"\r
\n" ); document.write( "\n" ); document.write( "\"5+=+44%2F6+%2B+b\"\r
\n" ); document.write( "\n" ); document.write( "\"b+=+5-22%2F3\"\r
\n" ); document.write( "\n" ); document.write( "\"b+=+15%2F3-22%2F3\"\r
\n" ); document.write( "\n" ); document.write( "\"b=+-7%2F3\"\r
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\n" ); document.write( "\n" ); document.write( "equation of the altitude to \"DE\": \r
\n" ); document.write( "\n" ); document.write( "\"+y+=++%2811%2F6%29x+-7%2F3\"\r
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\n" ); document.write( "\n" ); document.write( "slope of \"EF+=+%28-2-4%29%2F%288-5%29+=+-7%2F4+\"\r
\n" ); document.write( "\n" ); document.write( "altitude to \"EF\" : \"+-1%2Fm+=+-1%2F%28-7%2F4%29\" -> \"m+=+4%2F7\"\r
\n" ); document.write( "\n" ); document.write( "\"y+=+mx+%2B+b\" (substitute \"m+=+4%2F7\", \"x+=+-3\", \"y+=4\")\r
\n" ); document.write( "\n" ); document.write( "\"4=+-3%284%2F7+%29+%2B+b\"\r
\n" ); document.write( "\n" ); document.write( "\"4+=+-12%2F7+%2B+b\"\r
\n" ); document.write( "\n" ); document.write( "\"b+=+4%2B12%2F7\"\r
\n" ); document.write( "\n" ); document.write( "\"b=+40%2F7\"\r
\n" ); document.write( "\n" ); document.write( "equation of the altitude to \"EF\": \r
\n" ); document.write( "\n" ); document.write( "\"y+=+%284%2F7%29+x+%2B40%2F7\"
\n" ); document.write( " \r
\n" ); document.write( "\n" ); document.write( "intersection of the altitudes will be orthocenter\r
\n" ); document.write( "\n" ); document.write( "equation 1: \"y+=++%2811%2F6%29x+-7%2F3\"
\n" ); document.write( "equation 2: \"y+=%284%2F7%29+x+%2B40%2F7\"\r
\n" ); document.write( "\n" ); document.write( "Solving for \"x\" and \"y\":\r
\n" ); document.write( "\n" ); document.write( "\"%2811%2F6%29x+-7%2F3=%284%2F7%29+x+%2B40%2F7\"\r
\n" ); document.write( "\n" ); document.write( "\"%2811%2F6%29x+-%284%2F7%29+x+=+7%2F3%2B40%2F7\"\r
\n" ); document.write( "\n" ); document.write( "\"%2853+x%29%2F42=+169%2F21\"\r
\n" ); document.write( "\n" ); document.write( "\"x+=+338%2F53\"\r
\n" ); document.write( "\n" ); document.write( "\"x=+6.4\"\r
\n" ); document.write( "\n" ); document.write( "\"y+=++%2811%2F6%29x+-7%2F3\"\r
\n" ); document.write( "\n" ); document.write( "\"y+=++%2811%2F6%29%286.4%29+-7%2F3\"\r
\n" ); document.write( "\n" ); document.write( "\"y=+9.4\"\r
\n" ); document.write( "\n" ); document.write( "The coordinates are (\"6.4\", \"9.4\"). This is the orthocenter.\r
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