document.write( "Question 585139: What is sin(2θ)sinθ=cosθ using the interval 0 ≤ θ < 2 π? \n" ); document.write( "
Algebra.Com's Answer #373165 by lwsshak3(11628)\"\" \"About 
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What is sin(2θ)sinθ=cosθ using the interval 0 ≤ θ < 2 π?
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\n" ); document.write( "sin(2θ)sinθ=cosθ
\n" ); document.write( "2sinθcosθsinθ=cosθ
\n" ); document.write( "2sinθcosθsinθ-cosθ=0
\n" ); document.write( "cosθ(2sin^2θ-1)=0
\n" ); document.write( "cosθ=0
\n" ); document.write( "θ=π/2 and 3π/2
\n" ); document.write( "or
\n" ); document.write( "2sin^2θ-1=0
\n" ); document.write( "sin^2θ=1/2
\n" ); document.write( "sinθ=±1/√2=±√2/2
\n" ); document.write( "θ=π/4 and 3π/4 (in quadrants I and II where sin>0)
\n" ); document.write( "and 5π/4 and 7π/4 (in quadrants II and IV where sin<0)
\n" ); document.write( "..
\n" ); document.write( "θ=π/2, 3π/2, π/4, 3π/4, 5π/4 and 7π/4 \n" ); document.write( "
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