document.write( "Question 1109653: In triangle ABC a=4 b=11 and c=8 find m∠B? \n" ); document.write( "

Algebra.Com's Answer #724638 by Edwin McCravy(20059) $\"\"$ $\"About$

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In triangle ABC a=4 b=11 and c=8 find m∠B?

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document.write( "For the SSS case, we use the law of cosines:\r\n" );
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document.write( " b² = a² + c² - 2∙a∙c∙cos(B)\r\n" );
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document.write( "11² = 4² + 8² - 2∙4∙8∙cos(B)\r\n" );
document.write( "121 = 16 + 64 - 64∙cos(B)\r\n" );
document.write( "121 = 80 - 64∙cos(B)\r\n" );
document.write( " 41 = -64∙cos(B)\r\n" );
document.write( " = cos(B)\r\n" );
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document.write( "Use inverse cosine key on your calculator\r\n" );
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document.write( "B = 129.83844°\r\n" );
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document.write( "Ewin

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