document.write( "Question 852857: find the exact value of the trigonometric function, cos(u+v), given that sinu=5/13 and cos=-3/5
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Algebra.Com's Answer #513912 by stanbon(75887) $\"\"$ $\"About$

You can put this solution on YOUR website!
find the exact value of the trigonometric function,
\n" ); document.write( "cos(u+v) = cos(u)cos(v)-sin(u)sin(v)
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\n" ); document.write( "sin(u) = 5/13
\n" ); document.write( "cos[sqrt(13^2-5^2)]/13 = 12/13
\n" ); document.write( "Note: This implies that u is in QI\r
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\n" ); document.write( "\n" ); document.write( "cos(v) = -3/5
\n" ); document.write( "sin(v) = sqrt(25-9)/5 = 4/5
\n" ); document.write( "Note: This implies that v is in QII
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\n" ); document.write( "cos(u+v) = cos(u)cos(v)-sin(u)sin(v)
\n" ); document.write( "= (12/13)(-3/5) - (5/13)(4/5)
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\n" ); document.write( "= (-36 - 20)/65
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\n" ); document.write( "= -56/65
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\n" ); document.write( "= -0.8615
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\n" ); document.write( "Cheers,
\n" ); document.write( "Stan H.
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