document.write( "Question 421167: verify each of the following identities.
\n" ); document.write( " pls. help me solve this problem.. thank you in advance\r
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\n" ); document.write( "\n" ); document.write( "1. 1+cos theta=(tan^2theta)/(1-sec theta + tan^2theta)
\n" ); document.write( "2. cos 3x = cos^3x-3sin^2x cos x \n" ); document.write( "
Algebra.Com's Answer #294223 by lwsshak3(11628)\"\" \"About 
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1. 1+cos theta=(tan^2theta)/(1-sec theta + tan^2theta)
\n" ); document.write( " 2. cos 3x = cos^3x-3sin^2x cos x\r
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\n" ); document.write( "\n" ); document.write( "1.1+cos=tan^2/1-sec+tan^2
\n" ); document.write( "Starting with right-hand side,
\n" ); document.write( "tan^2/1-sec+tan^2
\n" ); document.write( "using identity:(tan^2x+1=sec^2x)
\n" ); document.write( "sec^2-1/1-sec+sec^2-1
\n" ); document.write( "=(sec+1)(sec-1)/sec^2-sec
\n" ); document.write( "=(sec+1)(sec-1)/sec(sec-1)
\n" ); document.write( "=(sec+1)/sec
\n" ); document.write( "=(sec/sec)+(1/sec)
\n" ); document.write( "=1+cos
\n" ); document.write( "verified:
\n" ); document.write( "left-hand side = right hand side
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\n" ); document.write( "2.cos3x=cos^3x-3sin^2xcosx
\n" ); document.write( "Starting with left-hand side
\n" ); document.write( "Using identity:(cos(x+y)=cosxcosy-sinxsiny)
\n" ); document.write( "cos3x=cos(x+2x)=cosxcos2x-sinxsin2x
\n" ); document.write( "Using identities:(Cos2x and sin2x)
\n" ); document.write( "=cosx(cos^2x-sin^2x)-sinx(2sinxcosx)
\n" ); document.write( "=cos^3x-sin^2xcosx-2sin^2cosx
\n" ); document.write( "=cos^3x-3sin^2cosx
\n" ); document.write( "verified:
\n" ); document.write( "left-hand side=right-hand side
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