document.write( "Question 1187102: Triangle ABC has vertices A(-2,3), B(1,-3) and C(p,1). For how many values of p is the triangle isosceles? \n" ); document.write( "
Algebra.Com's Answer #818058 by ikleyn(52781)\"\" \"About 
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\n" ); document.write( "Triangle ABC has vertices A(-2,3), B(1,-3) and C(p,1).
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\n" ); document.write( "\n" ); document.write( "            The solution by @MathLover1 is  FATALLY  INCOMPLETE.\r
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\n" ); document.write( "\n" ); document.write( "            There are several other,  different isosceles triangles,  that @MathLover1 missed/failed to find.\r
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\n" ); document.write( "\n" ); document.write( "            I came to bring the correct solution.\r
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\n" ); document.write( "\n" ); document.write( "First,  find the length of the side  AB.  It is  (apply the distance formula)\r
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\n" ); document.write( "\n" ); document.write( "         d = \"sqrt%28%281-%28-2%29%29%5E2+%2B+%28-3-3%29%5E2%29\" = \"sqrt%283%5E2+%2B+6%5E2%29\" = \"sqrt%2845%29\" = \"3%2Asqrt%285%29\".\r
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\n" ); document.write( "\n" ); document.write( "Next,  consider different cases.\r
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document.write( "Case AB = BC.\r\n" );
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document.write( "   In this case, BC = \"sqrt%2845%29\" = \"sqrt%28%28p-1%29%5E2+%2B+%281-%28-3%29%29%5E2%29\" = \"sqrt%28%28p-1%29%5E2%2B4%5E2%29\".\r\n" );
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document.write( "   Squaring both sides, you get\r\n" );
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document.write( "      45 = \"%28p-1%29%5E2+%2B+16\",\r\n" );
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document.write( "      45 = \"p%5E2+-+2p+%2B+1+%2B+16\"\r\n" );
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document.write( "      \"p%5E2+-+2p+-+28\" = 0\r\n" );
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document.write( "      \"p%5B1%2C2%5D\" = \"%282+%2B-+sqrt%282%5E2+-+4%2A%28-28%29%29%29%2F2\" = \"%282+%2B-+sqrt%284+%2B+4%2A28%29%29%2F2\" = \"1+%2B-+sqrt%2829%29\".\r\n" );
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document.write( "   Thus, it gives two different real values for p, and, hence, two different isosceles triangles with AB = BC.\r\n" );
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document.write( "   These two different isosceles triangles are shown in the Figure 1 below (blue lines).\r\n" );
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document.write( "   \r\n" );
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document.write( "                      Figure 1.  Two different triangles for case 1.\r\n" );
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document.write( "Case AB = AC.\r\n" );
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document.write( "   In this case, AC = \"sqrt%2845%29\" = \"sqrt%28%28p-%28-2%29%29%5E2+%2B+%281-3%29%5E2%29\" = \"sqrt%28%28p%2B2%29%5E2%2B2%5E2%29\".\r\n" );
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document.write( "   Squaring both sides, you get\r\n" );
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document.write( "      45 = \"%28p%2B2%29%5E2+%2B+4\",\r\n" );
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document.write( "      45 = \"p%5E2+%2B+4p+%2B+4+%2B+4\"\r\n" );
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document.write( "      \"p%5E2+%2B+4p+-+37\" = 0\r\n" );
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document.write( "      \"p%5B1%2C2%5D\" = \"%28-4+%2B-+sqrt%284%5E2+-+4%2A%28-37%29%29%29%2F2\" = \"%28-4+%2B-+sqrt%2816+%2B+4%2A37%29%29%2F2\" = \"-2+%2B-+sqrt%2841%29\".\r\n" );
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document.write( "   Thus, it gives two different real values for p, and, hence, two different isosceles triangles with AB = AC.\r\n" );
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document.write( "   These two different isosceles triangles are shown in the Figure 2 below (blue lines).\r\n" );
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document.write( "   \r\n" );
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document.write( "                      Figure 2.  Two different triangles for case 2.\r\n" );
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\n" ); document.write( "\n" ); document.write( "So,  in my post  I  shown  4  possible isosceles triangles,  missed by @MathLover1.\r
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\n" ); document.write( "\n" ); document.write( "The fifth triangle is the one found in her post.\r
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\n" ); document.write( "\n" ); document.write( "The  ANSWER  to the problem's question  IS :   5  triangles are possible.\r
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