document.write( "Question 1060297: Find the exact value of the trigonometric function given that sin u = 5/13 and cos v = -3/5 (Both are in Quadrant II.) sec (v - u) \n" ); document.write( "

Algebra.Com's Answer #675256 by Edwin McCravy(20060) $\"\"$ $\"About$

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document.write( "We have to pause here and use an identity:\r\n" );
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document.write( "we use it to find cos(u) from sin(u):\r\n" );
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document.write( "Multiply through by 169\r\n" );
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document.write( "Subtract 25 from both sides:\r\n" );
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document.write( "We can determine which sign + or - to use because\r\n" );
document.write( "we know that both are in Quadrant II, and the\r\n" );
document.write( "cosine is negative in quadrant II.  So \r\n" );
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document.write( "we can now substitute that in \r\n" );
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document.write( "But we still need sin(v).  So we go back to the identity:\r\n" );
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document.write( "we use it to find sin(v) from cos(v):\r\n" );
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document.write( "  \r\n" );
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document.write( "Multiply through by 25\r\n" );
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document.write( "Subtract 9 from both sides:\r\n" );
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document.write( "As before we can determine which sign + or - to use because\r\n" );
document.write( "we know that both are in Quadrant II, and the sine is\r\n" );
document.write( "positive in quadrant II.  So \r\n" );
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document.write( "we can now substitute that in \r\n" );
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document.write( "Answer: \r\n" );
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document.write( "Edwin

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