document.write( "Question 723889: Find all values of θ, to the nearest degree, that satisfy the equation 7cos cubedθ = 5cos squaredθ +cosθ in the interval 0< θ < 360 \n" ); document.write( "
Algebra.Com's Answer #443488 by lwsshak3(11628)\"\" \"About 
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Find all values of θ, to the nearest degree, that satisfy the equation 7cos cubedθ = 5cos squaredθ +cosθ in the interval 0< θ < 360
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\n" ); document.write( "7cos^3x=5cos^2x+cosx
\n" ); document.write( "7cos^3x-5cos^2x-cosx=0
\n" ); document.write( "cosx(7cos^2x-5cosx-1)=0
\n" ); document.write( "cosx=0
\n" ); document.write( "x=90º,270º
\n" ); document.write( "..
\n" ); document.write( "7cos^2x-5cosx-1)=0
\n" ); document.write( "solve for cos x by quadratic formula:
\n" ); document.write( "cosx≈-0.1629
\n" ); document.write( "using inverse cos key on calculator:
\n" ); document.write( "x≈99º, 261º( in quadrants II and III where cos<0)
\n" ); document.write( "or
\n" ); document.write( "cosx≈0.8772
\n" ); document.write( "using inverse cos key on calculator:
\n" ); document.write( "x≈28.7º, 331º( in quadrants I and IV where cos>0)
\n" ); document.write( "..
\n" ); document.write( "all values of θ in the interval 0< θ < 360: 90º, 270º, 99º, 261º, 28.7º, 331º \n" ); document.write( "
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