document.write( "Question 1056706: verify sin(3x)=sinx(4cos^2x-1) \n" ); document.write( "

Algebra.Com's Answer #671784 by htmentor(1343) $\"\"$ $\"About$

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using identities, we have:
\n" ); document.write( "sin(3x) = sin(2x+x) = sin(2x)cos(x) + sin(x)cos(2x)
\n" ); document.write( "and sin(2x) = 2sin(x)cos(x); cos(2x) = 2cos^2(x) - 1
\n" ); document.write( "so sin(3x) = 2sin(x)cos(x)*cos(x) + sin(x)(2cos^2(x) - 1) -> sin(x)(2cos^2(x)+2cos^2(x) - 1) -> sin(x)(4cos^2(x)-1)\r
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