document.write( "Question 817705: Solve it for 0\n" ); document.write( "cos(x+45)+cos(x-45)=radical 2
\n" ); document.write( "*both 45's are in degrees \n" ); document.write( "

Algebra.Com's Answer #492161 by lwsshak3(11628) $\"\"$ $\"About$

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cos(x+45)+cos(x-45)=radical 2
\n" ); document.write( "Identity: $\"cos%28s%29%2Bcos%28t%29=2cos%28%28s%2Bt%29%2F2%29cos%28%28s-t%29%2F2%29\"$
\n" ); document.write( "

\n" ); document.write( " $\"2cos%282x%2F2%29cos%28%2890%29%2F2%29=sqrt%282%29=2cos%28x%29cos%2845%29=sqrt%282%29\"$
\n" ); document.write( "2cos(x)cos(45)=√2
\n" ); document.write( "2cos(x)(√2/2)=√2
\n" ); document.write( "cos(x)=√2/√2=1
\n" ); document.write( "x=0
\n" ); document.write( "..
\n" ); document.write( "Check:
\n" ); document.write( "cos(x+45)+cos(x-45)
\n" ); document.write( "=cos(45)+cos(-45)=cos(x+45)+cos(x-45)=√2/2+√2/2=2√2/2=√2 \n" ); document.write( "

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