document.write( "Question 865410: If x+4=3sin(θ) for 0<θ<π/2 express cos(2θ) in terms of x.
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Algebra.Com's Answer #521679 by lwsshak3(11628)\"\" \"About 
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If x+4=3sin(θ) for 0<θ<π/2 express cos(2θ) in terms of x.
\n" ); document.write( "cos(2θ)=
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\n" ); document.write( "cos(2θ)==cos^2(θ)-sin^2(θ)
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\n" ); document.write( "x+4=3sin(θ)
\n" ); document.write( "sin(θ)=(x+4)/3
\n" ); document.write( "sin^2(θ)=(x+4)^2/9
\n" ); document.write( "cos^2(θ)=1-sin^2(θ)=1-(x+4)^2/9=(9-(x+4)^2)/9
\n" ); document.write( "cos(2θ)=(9-(x+4)^2)/9-(x+4)^2/9
\n" ); document.write( "cos(2θ=(9-2(x+4)^2)/9=9-2(x^2+8x+16)/9=(9-2x^2-16x-32)/9=(-2x^2-16x-23)/9
\n" ); document.write( "cos(2θ=-(2x^2+16x+23)/9 \n" ); document.write( "
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