document.write( "Question 1107134: Find the third vertex C(x,y) of an equilateral triangle if the other vertices are A(-4,-1) and B (4,3) \n" ); document.write( "
Algebra.Com's Answer #722119 by josgarithmetic(39618)\"\" \"About 
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Each triangle side is \"2sqrt%2810%29\", found using distance-formula. This means \"AB=BC=CA=2%2Asqrt%2810%29\".\r
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\n" ); document.write( "\n" ); document.write( "Slope of AB is \"1%2F2\", and then slope of the line perpendicular to AB and containing point C must be \"-2\". Also This perpendicular bisector line must contain midpoint of AB, which is (using Midpoint formula), (0,1).
\n" ); document.write( "This means, line containing point C is \"y=-2x%2B1\".\r
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\n" ); document.write( "\n" ); document.write( "\"sqrt%28%28-4-x%29%5E2%2B%28-1-%282x%2B1%29%29%5E2%29=2%2Asqrt%2810%29\"
\n" ); document.write( "and
\n" ); document.write( "\"sqrt%28%284-x%29%5E2%2B%283-%282x%2B1%29%29%5E2%29=2%2Asqrt%2810%29\"\r
\n" ); document.write( "\n" ); document.write( ".\r
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