document.write( "Question 353088: Given sin(x)= 2/3 What is the value cos(2x) \n" ); document.write( "

Algebra.Com's Answer #252356 by CharlesG2(834) $\"\"$ $\"About$

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Given sin(x)= 2/3 What is the value cos(2x)\r
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\n" ); document.write( "\n" ); document.write( "double-angle cosine formula --> cos(2x) = 1 - 2sin^2(x)\r
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\n" ); document.write( "\n" ); document.write( "sin(x) = 2/3
\n" ); document.write( "sin^2(x) = 4/9
\n" ); document.write( "cos(2x) = 1 - 2sin^2(x) = 1 - 2(4/9) = 1 - 8/9 = 1/9\r
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