document.write( "Question 548540: triangle PQR, with P=(3,6), Q=(4,1), R=(14,3), find the measure of the largest angle of the triangle PQR.\r
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Algebra.Com's Answer #357049 by Edwin McCravy(20055)\"\" \"About 
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triangle PQR, with P=(3,6), Q=(4,1), R=(14,3), find the measure of the largest angle of the triangle PQR.
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document.write( "The largest angle is at Q.  It looks like a right angle.\r\n" );
document.write( "If it is, then the slopes of the lines PQ and QR will be\r\n" );
document.write( "opposite signed reciprocals\r\n" );
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document.write( "Find the slope of PQ\r\n" );
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document.write( "m = \"%28y%5B2%5D-y%5B1%5D%29%2F%28x%5B2%5D-x%5B1%5D%29\"\r\n" );
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document.write( "m = \"%281-6%29%2F%284-3%29\"\r\n" );
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document.write( "m = \"%28-5%29%2F1\"\r\n" );
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document.write( "m = -5\r\n" );
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document.write( "Find the slope of QR\r\n" );
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document.write( "m = \"%28y%5B2%5D-y%5B1%5D%29%2F%28x%5B2%5D-x%5B1%5D%29\"\r\n" );
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document.write( "m = \"%283-1%29%2F%2814-4%29\"\r\n" );
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document.write( "m = \"2%2F10\"\r\n" );
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document.write( "m = \"1%2F5\"\r\n" );
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document.write( "-5 and \"1%2F5\" are opposite signed reciprocals, that is,\r\n" );
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document.write( "their product is -5·\"1%2F5\" = -1.\r\n" );
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document.write( "So PQ and QR are perpendicular, so angle Q is 90°\r\n" );
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document.write( "Edwin
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