document.write( "Question 988624: prove that for any triangle ABC, where a,b, and c are respectively
\n" ); document.write( "the sides opposite angles A,B, and C,
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Algebra.Com's Answer #609197 by Edwin McCravy(20060) $\"\"$ $\"About$

You can put this solution on YOUR website!

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document.write( "The law of cosines: \r\n" );
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document.write( "when solved for the cosines, give:\r\n" );
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document.write( "So the identity becomes to show that \r\n" );
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document.write( "On the left side multiply numerator and denominator by LCD = 2abc\r\n" );
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document.write( "Cancel terms that add to zero and collect like terms:\r\n" );
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document.write( "Rearrange the terms of the numerator to factor by grouping, \r\n" );
document.write( "factor 2ab out of the denominator:\r\n" );
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document.write( "Factor first two terms in numerator as the difference of squares.\r\n" );
document.write( "Factor -c² out of last two terms in numerator:\r\n" );
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document.write( "Factor (b²-a²) out of numerator:\r\n" );
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document.write( "Cancel (b²-a²)'s\r\n" );
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document.write( "That is the right side of the identity.\r\n" );
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document.write( "Edwin

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