document.write( "Question 1157259: 2cos2theta-sintheta=-1 \n" ); document.write( "

Algebra.Com's Answer #780115 by Boreal(15235) $\"\"$ $\"About$

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2(1-sin^2 t)-sin t=-1
\n" ); document.write( "2-2sin^2 t-sin t=-1
\n" ); document.write( "0=2sin^2t+sin^t-3
\n" ); document.write( "0=(2 sin t+3)(sin t -1)
\n" ); document.write( "sin t=1, and that occurs when theta=90 deg or pi/2 rad.
\n" ); document.write( "cos t=0 at pi/2
\n" ); document.write( "2 cos^2 pi/2-sin pi/2=0-1=-1 \n" ); document.write( "

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