document.write( "Question 1011415: The vertices of a triangle are (1,k), (4,-3) and (-9,7). If the area of triangle is 15 Sq. units, then find the value(s) of k. \n" ); document.write( "
Algebra.Com's Answer #627064 by MathLover1(20850)\"\" \"About 
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The vertices of a triangle are:
\n" ); document.write( " (\"1\",\"k\"),
\n" ); document.write( "(\"4\",\"-3\") and
\n" ); document.write( " (\"-9\",\"7\").
\n" ); document.write( "If the area of triangle is \"A=15+\" Sq. units, then find the value(s) of \"k\". \r
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\n" ); document.write( "\n" ); document.write( "We have a formula which can be directly used on the vertices of triangle to find its area.\r
\n" ); document.write( "\n" ); document.write( "If, (\"x%5B1%5D\", \"y%5B1%5D\"), (\"x%5B2%5D\", \"y%5B2%5D\") and (\"x%5B3%5D\", \"y%5B3%5D\") are the \r
\n" ); document.write( "\n" ); document.write( "coordinates of vertices of triangle then area of triangle is:
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\n" ); document.write( "\n" ); document.write( "you are given:\r
\n" ); document.write( "\n" ); document.write( "\"A=15+\" Sq. units
\n" ); document.write( "\"x%5B1%5D=1\"
\n" ); document.write( "\"x%5B2%5D=4\"
\n" ); document.write( "\"x%5B3%5D=-9\"
\n" ); document.write( "\"y%5B1%5D=k\"
\n" ); document.write( "\"y%5B2%5D=-3\"
\n" ); document.write( "\"y%5B3%5D=7\"\r
\n" ); document.write( "\n" ); document.write( "substitute it in\r
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\n" ); document.write( "\n" ); document.write( "\"15=+%281%2F2%29%281%2A%28-3-7%29%2B4%287-k%29%2B%28-9%29%28k%2B3%29%29\"\r
\n" ); document.write( "\n" ); document.write( "\"30=+%28-10%2B28-4k-9k-27%29\"\r
\n" ); document.write( "\n" ); document.write( "\"30=+-10%2B28-4k-9k-27\"\r
\n" ); document.write( "\n" ); document.write( "\"30=+-37%2B28-13k\"\r
\n" ); document.write( "\n" ); document.write( "\"30=+-9-13k\"\r
\n" ); document.write( "\n" ); document.write( "\"13k=+-9-30\"\r
\n" ); document.write( "\n" ); document.write( "\"13k=+-39\"\r
\n" ); document.write( "\n" ); document.write( "\"k=+-39%2F13\"\r
\n" ); document.write( "\n" ); document.write( "\"k=+-3\"\r
\n" ); document.write( "\n" ); document.write( "so, your points are:\r
\n" ); document.write( "\n" ); document.write( "(\"1\",\"-3\"),
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\n" ); document.write( "\n" ); document.write( "ss you can see from the graph, the length of the base of triangle is \"3\" units and height is \"10\" units\r
\n" ); document.write( "\n" ); document.write( "so, the area is: \"A=%281%2F2%29b%2Ah\"=>\"A=%281%2F2%293%2A10\"=>\"A=30%2F2\"=>\"A=15\" sq.units and it confirms that \"k=-3\"\r
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